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Medical Dictionary


disequilibrium (dis-e′kwi-lib′re-um)
A disturbance or absence of equilibrium. genetic d. a state in the genetic composition of a population which under selection may be expected to change toward an equilibrium or absorbing state. linkage d. a state involving two loci in which the probability of a joint gamete is not equal to the product of the probabilities of the constituent genes. The difference between these quantities is the increase of the d.; there are many causes of the d..

disfluency (dis-floo′en-se)
Inability to produce a smooth flow of speech sounds in connected discourse; the flow of speech is characterized by frequent interruptions and repetitions. [dis- + fluency]

disfluent (dis-floo′ent)
Relating to disfluency.

disgerminoma (dis-jer-mi-no′ma)
SYN: dysgerminoma.

Abbreviation for diffuse idiopathic skeletal hyperostosis.

A shallow container, usually concave. Petri d. a small, shallow, circular d. made of thin glass or clear plastic with a loosely fitting, overlapping cover used especially in microbiology for the cultivation of microorganisms on solid media; it is frequently referred to as a plate. Stender d. a flat shallow vessel used in staining sections.

disharmony (dis-har′mo-ne)
1. The state of being deranged or lacking in orderliness. 2. In a complex sound, the absence of a mathematical relationship among the frequencies of the fundamental tone and its overtones so that the frequencies of the overtones are not whole-number multiples or partials of the frequency of the fundamental tone. The auditory effect has a noisy or unpleasant quality, as opposed to music. occlusal d. 1. contacts of opposing occlusal surfaces of teeth which are not in harmony with other tooth contacts and with the anatomic and physiologic control of the mandible; 2. occlusions which do not coincide with their respective jaw relations. SEE ALSO: deflective occlusal contact.

Abbreviation for diisopropyl iminodiacetic acid or disofenin.

disimpaction (dis′im-pak′shun)
1. Separation of impaction in a fractured bone. 2. Removal of feces, usually manually, in fecal impaction.

disinfect (dis-in-fekt′)
To destroy pathogenic microorganisms in or on any substance or to inhibit their growth and vital activity.

disinfectant (dis-in-fek′tant)
1. Capable of destroying pathogenic microorganisms or inhibiting their growth activity. 2. An agent that possesses this property. complete d. a d. that kills both vegetative forms and spores. incomplete d. a d. that kills only the vegetative forms, leaving the spores uninjured.

disinfection (dis-in-fek′shun)
Destruction of pathogenic microorganisms or their toxins or vectors by direct exposure to chemical or physical agents. concurrent d. application of disinfective measures as soon as possible after discharge of infectious material from the body of an infected person, or after soiling of articles with such infectious discharges. terminal d. application of disinfective measures after the patient has been removed, e.g., by death, or has ceased to be a source of infection.

Physical or chemical process to destroy or remove small undesirable animal forms, particularly arthropods or rodents, present upon the person, clothing, or environment of an individual or domestic animals.

disinhibition (dis′in-hi-bish′un)
1. Removal of an inhibition, such as by a toxic or organic process. 2. Removal of an inhibitory effect by a stimulus, as when a conditioned reflex has undergone extinction but is restored by some extraneous stimulus.

disinsection, disinsectization (dis-in-sek′shun, dis′in-sek-ti-za′shun)
Freeing an area from insects. [L. dis-, apart, + insect]

disintegration (dis-in-te-gra′shun)
1. Loss or separation of the component parts of a substance, as in catabolism or decay. 2. Disorganization of psychic and behavioral processes. [dis- + L. integer, whole, intact]

disinvagination (dis′in-vaj-i-na′shun)
Relieving an invagination.

disjunction (dis-junk′shun)
The normal separation of pairs of chromosomes at the anaphase stage of meiosis I or II. [dis- + L. junctio, a joining, fr. jungo, pp. junctum, to join]

disk [TA]
1. A round, flat plate; any approximately flat circular structure. 2. SYN: lamella (2) . 3. In dentistry, a circular piece of thin paper or other material, coated with an abrasive substance, used for cutting and polishing teeth and fillings. [L. discus; G. diskos, a quoit, d.] A disks SYN: A bands, under band. acromioclavicular d. SYN: articular d. of acromioclavicular joint. Airy d. the image of a circular blur formed by a distant point source of light on the retina because of diffraction by the edge of the pupillary aperture where the diameter of the image decreases as the aperture increases. anisotropic disks SYN: A bands, under band. articular d. [TA] a plate or ring of fibrocartilage attached to the joint capsule and separating the articular surfaces of the bones for a varying distance, sometimes completely; it serves to adapt two articular surfaces that are not entirely congruent. SYN: discus articularis [TA] , fibrocartilago interarticularis, fibroplate, interarticular fibrocartilage, intraarticular cartilage (1) . articular d. of acromioclavicular joint [TA] the articular d. of fibrocartilage usually found between the acromial end of the clavicle and the medial border of the acromion. SYN: discus articularis acromioclavicularis [TA] , acromioclavicular d., Weitbrecht cartilage. articular d. of distal radioulnar joint [TA] the d. that holds together the distal ends of the radius and ulna; it is attached by its apex to a depression between the styloid process and distal surface of the head of the ulna, and by its base to the ridge separating the ulnar notch from the carpal surface of the radius. SYN: discus articularis radioulnaris distalis [TA] , radioulnar d., radioulnar articular d., triangular cartilage, triangular d. of wrist, triquetrous cartilage (1) . articular d. of sternoclavicular joint [TA] the fibrocartilaginous d. that subdivides the sternoclavicular joint into two cavities. SYN: discus articularis sternoclavicularis [TA] , sternoclavicular d., sternoclavicular articular d.. articular d. of temporomandibular joint [TA] the fibrocartilaginous plate that separates the joint into upper and lower cavities. SYN: discus articularis temporomandibularis [TA] , mandibular d., temporomandibular articular d.. blastodermic d. the aggregation of blastomeres of a telolecithal ovum after cleavage has occurred. blood d. SYN: platelet. Bowman disks disks resulting from transverse segmentation of striated muscular fiber treated with weak acids, certain alkaline solutions, or freezing. Burlew d. an abrasive-impregnated rubber wheel used in dentistry for polishing. SYN: Burlew wheel. choked d. SYN: papilledema. ciliary d. SYN: orbiculus ciliaris. cone disks membranous disks of flattened sacs about 14 nm thick that occur in the outer segment of cones of the retina. cuttlefish d. a circle of paper or thin plastic coated with ground cuttlefish bone; used, when attached to a mandrel and rotated by a dental handpiece, for fine smoothing and finishing of dental materials and tooth. diamond d. a steel d. with the cutting surface(s) covered with fine diamond chips, for use in a dental handpiece. embryonic d. SYN: germinal d.. emery disks disks of paper or other materials coated with emery powder used to abrade or smooth the surface of teeth or fillings. germinal d., germ d. the point in a telolecithal ovum where the embryo begins to be formed. SYN: embryonic d., germinal area, area germinativa. H d. SYN: H band. hair d. a richly innervated area of skin around a hair follicle, consisting of a thickened layer of epithelial cells in which ramify unmyelinated terminals of a single axon. Hensen d. SYN: H band. herniated d. protrusion of a degenerated or fragmented intervertebral d. into the intervertebral foramen with potential compression of a nerve root or into the spinal canal with potential compression of the cauda equina in the lumbar region or the spinal cord at higher levels. SYN: protruded d., ruptured d.. I d. SYN: I band. intercalated d. a specialized intercellular attachment of cardiac muscle comprising gap junctions, fascia adherens, and occasionally desmosomes. intermediate d. SYN: Z line. interpubic d. SYN: interpubic d.. intervertebral d. a d. interposed between the bodies of adjacent vertebrae. It is composed of an outer fibrous part (annulus fibrosus) that surrounds a central gelatinous mass (nucleus pulposus). SYN: discus intervertebralis [TA] , fibrocartilago intervertebralis, intervertebral cartilage. isotropic d. SYN: I band. mandibular d. SYN: articular d. of temporomandibular joint. Merkel tactile d. SYN: tactile meniscus. Newton d. a d. on which are seven colored sectors, each occupying proportionally the same space as the corresponding primary color in the spectrum; when the d. is rapidly rotated it appears white. optic d. [TA] an oval area of the ocular fundus devoid of light receptors where the axons of the retinal ganglion cell converge to form the optic nerve head; SYN: discus nervi optici [TA] , blind spot (3) , Mariotte blind spot, optic nerve head, optic papilla, papilla nervi optici, porus opticus. Placido da Costa d. SYN: keratoscope. proligerous d. SYN: cumulus oöphorus. protruded d. SYN: herniated d.. Q disks SYN: A bands, under band. radioulnar d., radioulnar articular d. SYN: articular d. of distal radioulnar joint. Ranvier disks tactile nerve endings, of cupped disklike form, in the skin. rod disks membranous disks of flattened sacs about 14 nm thick that occur in the outer segment of rods of the retina. ruptured d. SYN: herniated d.. sacrococcygeal d. a thin plate of fibrocartilage interposed between the sacrum and coccyx. sandpaper disks disks of paper coated with various grits of silica; used to abrade or smooth the surface of teeth or dental materials. stenopeic d., stenopaic d. a metallic or other opaque d. with a narrow slit through which one looks; used as a test for astigmatism. sternoclavicular d., sternoclavicular articular d. SYN: articular d. of sternoclavicular joint. stroboscopic d. a revolving d. that gives successive views of a moving object. tactile d. SYN: tactile meniscus. temporomandibular articular d. SYN: articular d. of temporomandibular joint. transverse d. one of the dark transverse bands seen on examining a striated muscular fiber under the microscope. triangular d. of wrist SYN: articular d. of distal radioulnar joint. Z d. SYN: Z line.

diskitis (dis-ki′tis)
SYN: discitis.

See disco-.

diskogram (dis′ko-gram)
The graphic record, usually radiographic, of diskography.

diskography (dis-kog′ra-fe)
Historically, radiographic demonstration of intervertebral disk by injection of contrast media into the nucleus pulposus. [disco- + G. grapho, to write]

dislocate (dis′lo-kat)
To luxate; to put out of joint.

dislocatio (dis-lo-ka′she-o)
SYN: dislocation. [L.] d. erecta a subglenoid dislocation of the shoulder in which the humerus is in an abducted postion with the head of the humerus displaced inferiorly.

dislocation (dis-lo-ka′shun)
Displacement of an organ or any part; specifically a disturbance or disarrangement of the normal relation of the bones at a joint. The direction of the d. is determined by the position of the distal part of the articulation. SYN: dislocatio, luxation (1) . [L. dislocatio, fr. dis-, apart, + locatio, a placing] d. of articular processes complete d. of one or both articular processes, usually with overriding of the inferior articular process of the vertebra above into a position anterior to the superior articular process of the vertebra below. SYN: locked facets. arytenoid d. separation of the cricoarytenoid joint with subluxation of the arytenoid cartilage. SYN: arytenoid subluxation. closed d. a d. not complicated by an external wound. SYN: simple d.. compound d. SYN: open d.. fracture d. d. associated with or accompanied by a fracture of one of the bones forming the articulation. Kienböck d. d. of semilunar bone. open d. a d. complicated by a wound opening from the surface down to the affected joint. SYN: compound d.. perilunar d. d. of carpal bones around the lunate, which remains in its normal anatomic position in relation to the radius; distinguish from d. of lunate, Kienböck d.. simple d. SYN: closed d..

dismember (dis-mem′ber)
1. To amputate an arm or leg. 2. To divide the body (corpus) in parts.

dismutase (dis′mu-tas)
Generic name for enzymes catalyzing the reaction of two identical molecules to produce two molecules in differing states of oxidation ( e.g., superoxide d.) or of phosphorylation ( e.g., glucose-1-phosphate phosphodismutase).

dismutation (dis′mu-ta′shun)
A reaction involving a single substance but producing two products; e.g., two molecules of acetaldehyde may react, producing an oxidation product (acetic acid) and a reduction product (ethyl alcohol).

disobliteration (dis′ob-lit-er-a′shun)
Opening of a pathologically closed channel.

disofenin (di′so-fen-in)
SYN: diisopropyl iminodiacetic acid.

disomic (di-so′mik)
Relating to disomy.

disomy (di′so-me)
1. The state of an individual or cell having two members of a pair of homologous chromosomes; the normal state in humans, in contrast to monosomy and trisomy. 2. An abnormal chromosome represented twice in a single cell. [G. dis, two, + soma, body]

disopromine (di-so-pro′men)
SYN: diisopromine.

disopyramide (di-so-pir′a-mid)
An antiarrhythmic drug resembling quinidine with substantial anticholinergic properties.

disorder (dis-or′der)
A disturbance of function, structure, or both, resulting from a genetic or embryonic failure in development or from exogenous factors such as poison, trauma, or disease. adjustment disorders 1. a group of mental and behavioral disorders in which the development of symptoms is related to the presence of some environmental stressor or life event and is expected to remit when the stress ceases; 2. a d. whose essential feature is a maladaptive reaction to an identifiable psychological stress, or stressors, that occurs within weeks of the onset of the stressors and persists for up to six months; the maladaptive nature of the reaction is indicated by impairment in occupational (including school) functioning, or in usual social activities or relationships with others, or with symptoms that are in excess of a normal or expectable reaction to the stressor. affective disorders a group of mental disorders characterized by a disturbance in mood. antisocial personality d. 1. an enduring and pervasive pattern characterized by continuous and chronic antisocial behavior with disregard for and violation of the rights and safety of others, beginning before the age of 15; early childhood signs include chronic lying, stealing, fighting, and truancy; in adolescence there may be unusually early or aggressive sexual behavior, excessive drinking, and use of illicit drugs, such behavior continuing in adulthood. 2. a DSM diagnosis that is established when the specified criteria are met. anxiety disorders a group of interrelated mental illnesses involving anxiety reactions in response to stress. The types include: 1) generalized anxiety, by far the most prevalent condition, which strikes slightly more females than males, mostly in the 20–35 age group; 2) panic d., in which a person suffers repeated panic attacks. Some 2–5% of Americans are subject to this ailment, about twice as many women as men; 3) obsessive-compulsive d., afflicting 2–3% of the U.S. population; 4) posttraumatic stress d., most frequent among combat veterans or survivors of major physical trauma; and 5) the phobias ( e.g., fear of snakes, crowds, confinement, heights, etc.), which on a minor scale affect about one in eight people in the U.S. See neurosis. articulation disorders errors in pronunciation including phoneme omissions, substitutions, distortions, and additions. Asperger d. 1. a pervasive developmental d. characterized by severe and enduring impairment in social skills and restrictive and repetitive behaviors and interests, leading to impaired social and occupational functioning but without significant delays in language development. 2. a DSM diagnosis that is established when the specified criteria are met. asthenic personality d. SYN: asthenic personality. attention deficit d. a d. of attention, organization and impulse control appearing in childhood and sometimes persisting to adulthood. Hyperactivity may be a feature, but is not necessary for the diagnosis. attention deficit hyperactivity d. 1. a d. of childhood and adolescence manifested at home, in school, and in social situations by developmentally inappropriate degrees of inattention, impulsiveness, and hyperactivity. 2. a DSM diagnosis that is established when the specified criteria are met. SYN: hyperactive child syndrome. autistic d. 1. a severe form of pervasive developmental d.. SEE ALSO: autism, infantile autism. 2. a DSM diagnosis that is established when the specified criteria are met. See autism, infantile autism. avoidant d. of adolescence See avoidant d. of childhood. avoidant d. of childhood a mental d. occurring in childhood or adolescence characterized by an excessive shrinking away from contact with people who are unfamiliar. avoidant personality d. 1. an enduring and pervasive pattern in adulthood characterized by hypersensitivity to rejection, humiliation, shame, feelings of inadequacy resulting in social inhibition, and an unwillingness to enter into relationships without unusually strong guarantees of uncritical acceptance. 2. a DSM diagnosis that is established when the specified criteria are met. SYN: avoidant personality. behavior d. general term used to denote mental illness or psychological dysfunction, specifically those mental, emotional, or behavioral subclasses for which organic correlates do not exist. See antisocial personality d.. bipolar d. an affective d. characterized by the occurrence of alternating periods of euphoria (mania) and depression. SYN: manic-depressive psychosis. body dysmorphic d. 1. a psychosomatic (somatoform) d. characterized by preoccupation with some imagined defect in appearance in a normal-appearing person. 2. a DSM diagnosis that is established when the specified criteria are met. SYN: dysmorphophobia. borderline personality d. 1. an enduring and pervasive pattern that begins by early adulthood and is characterized by impulsivity and unpredictability, unstable interpersonal relationships, inappropriate or uncontrolled affect, especially anger, identity disturbances, rapid shifts of mood, suicidal acts, self-mutilations, job and marital instability, chronic feelings of emptiness or boredom, and intolerance of being alone. 2. a DSM diagnosis that is established when the specific criteria are met. character d. an older term referring to a group of behavioral disorders, now replaced by a more general term, personality d.. conduct d. 1. a mental d. of childhood or adolescence characterized by a persistent pattern of violating societal norms and the rights of others; children with the d. may exhibit physical aggression, cruelty to animals, vandalism and robbery, along with truancy, cheating, and lying. 2. a DSM diagnosis that is established when the specified criteria are met. See antisocial personality d.. conversion d. 1. a mental d. in which an unconscious emotional conflict is expressed as an alteration or loss of physical functioning, usually controlled by the voluntary nervous system. 2. a DSM diagnosis that is established when the specified criteria are met. cumulative trauma disorders (CTD) chronic disorders involving connective tissue (muscles, tendons) and nerve, often resulting from work-related physical activities. SYN: repetitive strain disorders, repetitive stress disorders. cyclothymic d. SYN: cyclothymia. cyclothymic personality d. SYN: cyclothymic personality. delusional d. a severe mental d. characterized by the presence of delusions. The delusions may be related to paranoid, grandiose, somatic, or erotic themes. dependent personality d. 1. an enduring and pervasive pattern in adulthood characterized by submissive and clinging behavior and excessive reliance on others to meet one's emotional, social, or economic needs. 2. a DSM diagnosis that is established when the specified criteria are met. SYN: dependent personality. depersonalization d. 1. a d. characterized by persistent or recurrent experiences of detachment from one's mental processes or body, as if one is an automaton, an outside observer, or in a dream; reality testing remains intact and there is clinically significant distress impairment. 2. a DSM diagnosis is established when the specified criteria are met. dissociative disorders a group of mental disorders characterized by disturbances in the functions of identity, memory, consciousness, or perception of the environment; this group includes dissociative (older term, psychogenic) amnesia, dissociative fugue, dissociative identity (older term, multiple personality) d., and depersonalization d.. dissociative identity d. 1. a d. in which two or more distinct conscious personalities alternately prevail in the same person, sometimes without any one personality being aware of the other(s). 2. a DSM diagnosis that is established when the specified criteria are met. SYN: multiple personality. dysthymic d. 1. a chronic disturbance of mood characterized by mild depression or loss of interest in usual activities. See depression. 2. a DSM diagnosis is established when the specified criteria are met. eating disorders a group of mental disorders including anorexia nervosa, bulimia nervosa, pica, and rumination d. of infancy. emotional d. mental illness, behavior d.. erotomanic d. the false belief that one is loved by another such as a movie star or a casual acquaintance. factitious d. a mental d. in which the individual intentionally produces symptoms of illness or feigns illness for psychological reasons rather than for environmental goals. familial bipolar mood d. bipolar mood d. commonly inherited as an autosomal dominant [MIM*125480] trait and also occasionally as an X-linked one [MIM*309200]. functional d. a d. characterized by physical symptoms with no known or detectable organic basis. See behavior d., neurosis. SYN: functional disease, functional illness. gender identity disorders 1. a mental d. in children, adolescents, or adults characterized by a strong and enduring cross-gender identification that manifests in insistence that one is, or desires to be, the other sex; this d. involves persistent discomfort with one's assigned sex or the gender role of one's sex, such that there is clinically significant distress or impairment in functioning, often leading to adopting to various degrees the gender role of the other sex. 2. a DSM diagnosis that is established when the specific criteria are met. SEE ALSO: transsexualism. generalized anxiety d. 1. chronic, repeated episodes of anxiety reactions; a psychological d. in which anxiety or morbid fear and dread accompanied by autonomic changes are prominent features. 2. a DSM diagnosis that is established when the specified criteria are met. See anxiety. grandiose type of paranoid d. a delusion in which the person believes that he or she possesses some great but unrecognized talent or insight, or has made an important discovery, with subsequent efforts toward official or public recognition. histrionic personality d. 1. an enduring and pervasive pattern of behavior in adulthood characterized by excessive, dramatic, and shallow emotionality; attention-seeking; and demands for approval and reassurance, beginning in early childhood and present in a variety of contexts. 2. a DSM diagnosis that is established when the specified criteria are met. SYN: hysterical personality d., hysterical personality. hysterical personality d. SYN: histrionic personality d.. identity d. a mental d. in which one suffers severe distress regarding one's ability to reconcile aspects of the self into a coherent acceptable sense of self. immune complex d. SYN: immune complex disease. immunoproliferative disorders disorders in which there is a continuing proliferation of cells of the immune system that can result in γ-globulin abnormalities such as in chronic lymphocytic leukemia, “macroglobulinemias,” and multiple myeloma. impulse control d. a group of mental disorders characterized by a person's failure to resist an impulse to perform some act harmful to self or to others; includes pathologic gambling, pedophilia, kleptomania, pyromania, trichotillomania, intermittent and isolated explosive disorders. induced psychotic d. a severe mental d. brought about by a toxic agent such as a drug or hallucinogen. See psychosis. intermittent explosive d. 1. a d. that may begin in early childhood, or following head injury at any age, characterized by repeated acts of violent, aggressive behavior in otherwise normal persons that is markedly out of proportion to the event that provokes it. 2. a DSM diagnosis that is established when the specified criteria are met. SYN: dyscontrol, episodic dyscontrol syndrome. internet addiction d. a posited clinical syndrome involving excessive time spent “surfing the net”; without clearly established criteria or etiology. ion channel disorders a number of diseases, mostly inherited and episodic in nature, caused by dysfunction of the calcium, chloride, potassium, or sodium channels of nerve or muscle; the inherited myotonias and periodic paralyses are included in this category; there is usually dominant inheritance, with the primary defect due to mutations of gene encoding on locus 7q32, 17q, or 1q31-32. SYN: channelopathies. isolated explosive d. a d. of impulse control characterized by a single episode of failure to resist a violent, externally directed act which had serious impact on others. jealous type of paranoid d. the false belief that one's spouse or lover is unfaithful, leading to repeated confrontation, or the taking of extraordinary steps to intervene in the imagined infidelity. late luteal phase dysphoric d. SYN: premenstrual syndrome. LDL receptor d. abnormality in clearance of LDL from the plasma due to abnormality in LDL receptor activity; causes hypercholesterolemia. lymphoplasmacellular disorders term used to refer to a group of disorders including plasmacytoma, multiple myeloma, lymphoplasmacytic lymphoma, MALT lymphoma, and amyloidosis. major mood d. See bipolar d., affective psychosis, endogenous depression, dysthymia, manic-depressive d.. manic-depressive d. obsolete term for bipolar d.. mental d. a psychological syndrome or behavioral pattern that is associated with subjective distress and/or objective impairment. SEE ALSO: mental illness, behavior d.. mitochondrial disorders a group of diverse hereditary disorders caused by genetic mutation of mitochrondrial DNA; includes ragged red fiber myopathy; progressive external ophthalmoplegia; Leigh syndrome; myoclonic epilepsy with ragged red fiber myopathy (MERRF); mitochondrial myopathy, encephalopathy, lacta cidosis, and stroke (MELAS); and Lieber optic neuropathy. mood disorders a group of mental disorders involving a disturbance of mood, accompanied by either a full or partial manic or depressive syndrome that is not due to any other mental d.. Mood refers to a prolonged emotion that colors the whole psychic life; it generally involves either depression or elation; e.g., manic episode, major depressive episode, bipolar disorders, and depressive d. (see separate entries for each). multiple personality d. older term for dissociative identity d.. narcissistic personality d. 1. a pervasive pattern in adulthood of self-centeredness, self-importance, lack of empathy for others, sense of entitlement, and viewing others largely as objects to meet one's needs, manifested in a variety of contexts. 2. a DSM diagnosis that is established when the specified criteria are met. neuropsychologic d. cerebral dysfunction from any physical cause manifested by changes in mood, behavior, perception, memory, cognition, or judgment and/or psychophysiology. neurotic d. SYN: neurosis. obsessive-compulsive d. 1. a type of anxiety d. whose essential feature is recurrent obsessions, persistent, intrusive ideas, thoughts, impulses or images, or compulsions (repetitive, purposeful, and intentional behaviors performed in response to an obsession) sufficiently severe to cause marked distress, be time-consuming, or significantly interfere with the individual's normal routine, occupational functioning, or usual social activities or relationships with others. 2. a DSM diagnosis that is established when the specified criteria are met. SEE ALSO: obsessive-compulsive personality d.. obsessive-compulsive personality d. 1. a pervasive pattern in adulthood characterized by unattainable perfectionism; preoccupation with rules, details, and orderliness; unreasonable attempts to control others; excessive devotion to work; and rumination to the point of indecisiveness, all at the expense of flexiblity, openness, and efficiency. 2. a DSM diagnosis that is established when the specified criteria are met. SYN: compulsive personality, obsessive personality, obsessive-compulsive personality. oppositional d. SYN: oppositional defiant d.. oppositional defiant d. 1. a d. of childhood or adolescence characterized by a recurrent pattern of negativistic, hostile, and disobedient behavior toward authority figures. 2. a DSM diagnosis that is established when the specified criteria are met. SYN: oppositional d.. organic mental d. a psychological, cognitive, or behavioral abnormality associated with transient or permanent dysfunction of the brain, usually characterized by the presence of an organic brain syndrome. overanxious d. a mental d. of childhood or adolescence marked by excessive worrying and fearful behavior not related specifically to separation or due to recent stress, now included within generalized anxiety d.. panic d. recurrent panic attacks that occur unpredictably. See generalized anxiety d.. paranoid d. SYN: persecutory type of paranoid d.. paranoid personality d. 1. a personality d. that is less debilitating than is the paranoid or delusional paranoid d.; the essential feature is a pervasive and unwarranted tendency, beginning in early adulthood and present in a variety of contexts, to misinterpret the actions of others as deliberately exploitive, harmful, demeaning, or threatening. 2. a DSM diagnosis that is established when the specified criteria are met. SYN: paranoid personality. persecutory type of paranoid d. one of the most common of the types of paranoid disorders, it involves a single theme or series of connected themes, such as being conspired against, cheated, spied on, followed, poisoned or drugged, maligned, harassed, or obstructed in the pursuit of long-term goals; small slights may be exaggerated and become the focus of a delusional system. See paranoia. Cf.:paranoid personality d.. SYN: paranoid d.. personality d. general term for a group of behavioral disorders characterized by usually lifelong ingrained maladaptive patterns of subjective internal experience and deviant behavior, lifestyle, and social adjustment, which patterns may manifest in impaired judgement, affect, impulse control and interpersonal functioning. pervasive developmental d. a group of mental disorders of infancy, childhood, or adolescence characterized by distortions in the acquisition of the multiple basic psychologic funtions necessary for the elaboration of social skills, language skills, and imagination; also characterized by restricted or stereotypical activities and interests. SEE ALSO: Rett syndrome, Asperger d.. plasma iodoprotein d. familial goiter. posttraumatic stress d. 1. development of characteristic symptoms following a psychologically traumatic event that is generally outside the range of usual human experience; symptoms include numbed responsiveness to environmental stimuli, a variety of autonomic and cognitive dysfunctions, and dysphoria. 2. a DSM diagnosis that is established when the specified criteria are met. premenstrual dysphoric d. 1. a pervasive pattern occurring during the last week of the luteal phase in most menstrual cycles for at least a year and remitting within a few days of the onset of the follicular phase, with some combination of depressed mood, mood lability, marked anxiety, or irritability; various specific physical symptoms; and significant functional impairment; the symptoms are comparable in severity to those seen in a major depressive episode, distinguishing this d. from the far more common premenstrual syndrome. SEE ALSO: premenstrual syndrome. 2. a specified set of criteria in the DSM, proposed for the purpose of futher research. psychogenic pain d. a d. in which the principal complaint is pain that is out of proportion to objective findings and that is related to psychological factors. psychosomatic d., psychophysiologic d. a d. characterized by physical symptoms of psychic origin, usually involving a single organ system innervated by the autonomic nervous system; physiological and organic changes stem from a sustained disturbance. psychotic d. SYN: psychosis. reactive attachment d. 1. a mental d. of infancy or early childhood characterized by disturbed social relatedness; thought to be caused by grossly pathologic care. 2. a DSM diagnosis that is established when the specified criteria are met. REM behavior d. a d. characterized by lack of the atonia of voluntary muscles that normally occurs in REM sleep. repetitive strain disorders SYN: cumulative trauma disorders. repetitive stress disorders SYN: cumulative trauma disorders. rumination d. 1. a mental d. occurring in infancy characterized by repeated regurgitation of food, usually accompanied by weight loss or failure to gain weight. 2. a DSM diagnosis that is established when the specified criteria are met. schizoid personality d. 1. an enduring and pervasive pattern of behavior in adulthood characterized by social withdrawal, emotional coldness or aloofness or restriction, and indifference to others. 2. a DSM diagnosis that is established when the specific criteria are met. SYN: schizoid personality. schizophreniform d. (skiz′o-fren′i-form) 1. a d. whose essential features are identical with those of schizophrenia, with the exception that the duration including prodromal, active, and residual phases is less than six months. 2. a DSM diagnosis that is established when the specified criteria are met. schizotypal personality d. 1. an enduring and pervasive pattern of behavior in adulthood characterized by discomfort with and reduced capacity for close relationships, cognitive or perceptual distortions, and eccentric behavior. 2. a DSM diagnosis that is established when the specific criteria are met. SYN: schizotypal personality. seasonal affective d. (SAD) a depressive mood d. that occurs at approximately the same time year after year and spontaneously remits at the same time each year. The most common type is winter depression and it is characterized by morning hypersomnia, low energy, increased appetite, weight gain, and carbohydrate craving, all of which remit in the spring. separation anxiety d. 1. a mental d. occurring in childhood characterized by excessive anxiety when the child is separated from someone to whom the child is attached, usually a parent. 2. a DSM diagnosis that is established when the specified criteria are met. sexual disorders a group of behavioral and psychophysiologic disorders in which there is symptomatic variability in sexual functioning, including either the eroticized behavior associated with sexual activity (the paraphilias) or with disturbances of desire, arousal, and orgasm. shared psychotic d. SYN: folie à deux. sleep terror d. night terrors. somatization d. 1. a mental d. characterized by presentation of a complicated medical history and of physical symptoms referring to a variety of organ systems, but without a detectable or known organic basis. See conversion, hysteria, Briquet syndrome. 2. a DSM diagnosis that is established when the specified criteria are met. somatoform d. a group of disorders in which physical symptoms suggesting physical disorders for which there are no demonstrable organic findings or known physiologic mechanisms, and for which there is positive evidence, or a strong presumption that the symptoms are linked to psychological factors; e.g., hysteria, conversion d., hypochondriasis, pain d., somatization d., body dysmorphic d., and Briquet syndrome. substance abuse disorders a group of mental disorders in which maladaptive behavioral and biologic changes are associated with regular use of alcohol, drugs, and related substances that affect the central nervous system and result in failure to meet significant obligations in personal and social functioning. substance dependence d. a maladaptive pattern of use of alcohol, drugs, or other substances, with tolerance and/or withdrawal symptoms, drug-seeking behavior, and lack of success in discontinuation of use, to the detriment of social, interpersonal, and occupational activities. substance-induced organic mental disorders mental disorders caused by use of drugs, e.g., cocaine, alcohol, etc. thought d. SYN: thought process d.. thought process d. an intellectual function symptom of schizophrenia, manifested by irrelevance and incoherence of verbal productions ranging from simple blocking and mild circumstantiality to total loosening of associations. SYN: thought d.. triple repeat disorders a group of hereditary disorders in which a gene mutation on a specific chromosome produces an abnormal form of protein terminated by a long chain of amino acid glutamate repeats; includes Huntington disease, Kennedy disease, Machado-Joseph disease, myotonic dystrophy, fragile X syndrome, and some spinal cerebellar disorders. visceral d. an obsolete term used in reference to psychosomatic d..

disorganization (dis-or′gan-i-za′shun)
Destruction of an organ or tissue with consequent loss of function.

disorientation (dis′or-e-en-ta′shun)
Loss of the sense of familiarity with one's surroundings (time, place, and person); loss of one's bearings.

disparate (dis′pa-rat)
Unequal; not alike. [L. disparo, pp. -atus, to separate, fr. paro, to prepare]

disparity (dis-par′i-te)
The condition of being disparate. [L. dispar, dissimilar] fixation d. the amount of heterophoria possible with fusion present. retinal d. the slight difference in retinal images that arises because of the lateral separation of the two eyes that stimulates stereoscopic vision.

dispensary (dis-pen′ser-e)
1. A physician's office, especially the office of one who dispenses medicines. 2. The office of a hospital pharmacist, where medicines are given out on physicians' orders. 3. An outpatient department of a hospital. [L. dis-penso, pp. -atus, to distribute by weight, fr. penso, to weigh]

Dispensatory (dis-pen′sa-to-re)
A work originally intended as a commentary on the Pharmacopeia, but now more of a supplement to that work, which contains an account of the sources, mode of preparation, physiologic action, and therapeutic uses of most of the agents, official and nonofficial; used in the treatment of disease. [L. dispensator, a manager, steward; see dispensary]

dispense (dis-pens′)
To give out medicine and other necessities to the sick; to fill a medical prescription.

dispermy, dispermia (di′sper-me, di-sperm′e-a)
Entrance of two spermatozoa into one ovum.

dispersal (dis-per′sal)
SYN: dispersion (1) . flash d. the property of rapid disintegration of a tablet when placed on the tongue.

disperse (dis-pers′)
To dissipate, to cause disappearance of, to scatter, to dilute.

dispersion (dis-per′zhun)
1. The act of dispersing or of being dispersed. SYN: dispersal. 2. Incorporation of the particles of one substance into the mass of another, including solutions, suspensions, and colloidal dispersions (solutions). 3. Specifically, what is usually called a colloidal solution. 4. The extent or degree in which values of a statistical frequency distribution are scattered about a mean or median value. [L. dispersio] coarse d. SYN: suspension (4) . colloidal d. SYN: colloidal solution. molecular d. d. in which the dispersed phase consists of individual molecules; if the molecules are of less than colloidal size, the result is a true solution. optic rotatory d. (ORD) the change in optic rotation with the wavelength of the incident monochromatic polarized light; the displacement of the former from zero within the absorption band is known as the Cotton effect. temporal d. asynchronous repolarization of myocardial fibers that predisposes to abnormal current flow and ectopic rhythms (especially with bradyarrhythmias or ventricular tachyarrhythmias).

dispersity (dis-per′si-te)
The extent to which the dimensions of particles have been reduced in colloid formation.


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