Medical Dictionary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

auxochrome (awk′so-krom)
The chemical group within a dye molecule by which the dye is bound to reactive end groups in tissues. The a. enhances the intensity of absorption. [auxo- + G. chroma, color]

auxodrome (awk′so-drom)
A course of growth as plotted on a Wetzel grid. [auxo- + G. dromos, course]

auxoflore (awk′so-flor)
An atom or group of atoms that, by its presence in a molecule, shifts the latter's fluorescent radiation in the direction of the shorter wavelength, or increases the fluorescence. Cf.:bathoflore.

auxogluc (awk′so-gluk)
An atomic grouping that, when present in a molecule, intensifies its sweetness. [G. auxano, to increase, + glykys, sweet]

auxotonic (awk-so-ton′ik)
Denoting the condition in which a contracting muscle shortens against an increasing load. Cf.:isometric (2) , isotonic (3) .

auxotox (awk′so-toks)
An atomic grouping that, when present in a molecule, intensifies its poisonous characteristics. [G. auxano, to increase, + toxikon, poison]

auxotroph (awk′so-trof)
A mutant microorganism that requires some nutrient that is not required by the organism (prototroph) from which the mutant was derived. Cf.:polyauxotroph, monoauxotroph. [auxo- + G. trophe, nourishment]

auxotrophic (awk-so-trof′ik, -tro′fik)
Pertaining to an auxotroph.

AV
Abbreviation for arteriovenous; atrioventricular.

A–V node
Atrioventricular node: a small mass of tissue that is situated in the wall of the right atrium adjacent to the septum between the atria, passes impulses received from the sinoatrial node to the ventricles by way of the bundle of His, and in some pathological states replaces the sinoatrial node as pacemaker of the heart.

ava
Abbreviation for arteriovenous anastomosis.

avalvular (a-val′vu-lar)
Nonvalvular; without valves.

avascular (a-vas′ku-ler, -a)
Without blood or lymphatic vessels; may be a normal state as in certain forms of cartilage, or the result of disease. SYN: nonvascular.

avascularization (a-vas′ku-lar-i-za′shun, a-)
1. Expulsion of blood from a part, as by means of a tourniquet or other means of arterial compression. 2. Loss of vascularity, as by scarring.

AVC
Abbreviation for atrioventricular conduction.

AVD
Abbreviation for atrioventricular dissociation.

Avellis
Georg, German laryngologist, 1864–1916. See A. syndrome.

avenin (a-ve′nin)
A prolamine, containing about 25% glutamyl residues, found in oats (Avena) and in various legumes; considered highly nutritious. SYN: legumin, plant casein.

average
A value that represents or summarizes the relevant features of a set of values; it is usually computed by a mathematical manipulation of the individual values in a set. [M.E. averays, loss from damage to ship or cargo, fr. It. avaris, fr. Ar. 'awariya, damaged goods, + damage] pure-tone a. a. in decibels of the thresholds for pure tones at 500, 1000, and 2000 Hz.

avermectins
A group of endectocidal drugs that includes ivermectin.

aVF, aVL, aVR
Abbreviation for augmented electrocardiographic leads from the foot (left), left arm, and right arm, respectively.

Aviadenovirus (a′ve-ad′e-no-vi′rus)
A genus of viruses (family Adenoviridae) that includes types of viruses found in birds. [L. avis, bird, + G. aden, gland, + virus]

avian (a′ve-an)
Pertaining to birds. [L. avis, bird]

avidin (av′i-din)
A glycoprotein, obtained from egg whites, which possesses a high affinity for biotin. Labeled a. is allowed to bind to biotin-tagged antibodies in order to amplify antigen-antibody reactions that may be difficult to visualize. Ingestion of a. can cause a biotin deficiency. SYN: antibiotin. [L. avidus, eager fr. aveo, to crave + -in]

avidity (a-vid′i-te)
The binding strength of an antibody for an antigen. [L. avidus, greedy, eager fr. aveo, to crave]

Avipoxvirus (a′ve-poks-vi′rus)
The genus of viruses (family Poxviridae) that includes the poxviruses of birds, including canarypox and fowlpox viruses. [L. avis, bird, + pox + virus]

avirulent (a-vir′u-lent)
Not virulent.

avitaminosis (a-vi′ta-min-o′sis)
Properly, hypovitaminosis. conditioned a. a. caused by any number of pathologic states or dysfunctions in which the supply of a vitamin absorbed by the body is inadequate for the needs under particular circumstances; e.g., the reduced bacterial synthesis of the vitamins in the alimentary canal produced by antibiotic agents.

avivement (ah-vev-maw′)
Obsolete term for the excision of the edges of a wound to assist the healing process. [Fr. aviver, to quicken, revive]

AV node
Abbreviation for atrioventricular node.

Avogadro
Amadeo, Italian physicist, 1776–1856. See A. constant, A. hypothesis, A. law, A. number, A. postulate.

avoirdupois (av′er-du-poyz′)
A system of weights in which 16 ounces make a pound, equivalent to 453.59237 g. See Weights and Measures appendix. [Fr. to have weight, corrupted fr. O. Fr. avoir, property, + de, of, + pois, weight]

AVP
Abbreviation for antiviral protein; arginine vasopressin.

A-V shunt
Abbreviation for arteriovenous shunt.

avulsion (a-vul′shun)
A tearing away or forcible separation. Cf.:evulsion. [L. a-vello, pp. -vulsus, to tear away] nerve a. the tearing away of a peripheral nerve at its point of origin from its parent nerve due to traction. root a. the tearing away of the anterior and posterior primary nerve roots from the spinal cord, due to severe traction; most often the C5 through T1 roots are affected. tooth a. the traumatic separation of a tooth from its alveolus.

AW
Abbreviation for atomic weight.

ax
Abbreviation for axis.

axenic (a-zen′ik)
Sterile, denoting especially a pure culture. Also used to denote “germ-free” animals born and raised in a sterile environment. SEE ALSO: gnotobiote. [G. a- priv. + xenos, foreign]

axerophthol (ak′ser-of′thol)
SYN: vitamin A. [antixerophthalmic + -ol]

axes (ak′sez)
Plural of axis.

axial (ak′se-al)
1. [TA] Relating to an axis. SYN: axialis [TA] , axile. 2. Relating to or situated in the central part of the body, in the head and trunk as distinguished from the limbs, e.g., a. skeleton. 3. In dentistry, relating to or parallel with the long axis of a tooth. 4. In radiology, an a. image is one obtained by rotating around the axis of the body, producing a transverse planar image, i.e., a section transverse to the axis.

axialis [TA]
SYN: axial (1) .

axifugal (ak-sif′u-gal)
Extending away from an axis or axon. SYN: axofugal. [L. axis + fugio, to flee from]

axil (ak′sil)
SYN: axilla.

axile (ak′sil)
SYN: axial (1) .

axilla, gen. and pl. axillae (ak′sil′a, ak-sil′e) [TA]
The space below the shoulder joint, bounded by the pectoralis major anteriorly, the latissimus dorsi posteriorly, the serratus anterior medially, and the humerus laterally; it has a superior opening between the clavicle, scapula, and first rib (cervicoaxillary canal), and an inferior opening or floor covered by the axillary fascia and skin; it contains the axillary artery and vein, the infraclavicular part of the brachial plexus, axillary lymph nodes and vessels, and areolar tissue. SYN: armpit, axil, axillary cavity, axillary fossa, axillary space, fossa axillaris, maschale. [L.]

axillary (ak′sil-ar-e)
Relating to the axilla. SYN: alar (2) .

axio-
An axis. SEE ALSO: axo-. [L. axis]

axiobuccal (ak′se-o-buk′al)
Referring to the junction of the axial and buccal planes of a tooth, usually a line.

axiobuccogingival (ak′se-o-buk-o-jin′ji-val)
Referring to the junction of the axial, buccal and gingival planes of teeth; usually a point.

axioincisal (ak′se-o-in-si′sal)
Referring to the line angle formed by the junction of the incisal edge and axial walls of a tooth.

axiolabial (ak′se-o-la′be-al)
Referring to the line angle of a cavity formed by the junction of the axial and the labial walls of a tooth.

axiolabiolingual (ak′se-o-la′be-o-ling′gwal)
Referring to a section from labial to lingual along the longitudinal axis of a tooth.

axiolingual (ak′se-o-ling′gwal)
Referring to the line angle of a cavity formed by the junction of an axial and a lingual wall of a tooth.

axiolinguocervical (ak′se-o-ling′gwo-ser′vi-kal)
Referring to the point angle formed by the junction of an axial, lingual, and cervical (gingival) wall of a tooth cavity.

axiolinguoclusal (ak′se-o-ling′gwo-kloo′sal)
Referring to the point angle formed by the junction of an axial, lingual, and occlusal wall of a tooth cavity.

axiolinguogingival (ak′se-o-ling′gwo-jin′ji-val)
Referring to the point angle formed by the junction of an axial, lingual, and gingival (cervical) wall of a tooth cavity.

axiomesial (ak′se-o-me′ze-al)
Referring to the line angle of a tooth cavity formed by the junction of an axial and a mesial wall.

axiomesiocervical (ak′se-o-me′ze-o-ser′vi-kal)
Referring to the point angle formed by the junction of an axial, mesial, and cervical (gingival) wall of a tooth cavity.

axiomesiodistal
See a. plane.

axiomesiogingival (ak′se-o-me′ze-o-jin′ji-val)
Referring to the point angle formed by an axial, mesial, and gingival (cervical) wall of a tooth cavity.

axiomesioincisal (ak′se-o-me′ze-o-in-si′sal)
Referring to the point angle formed by the junction of an axial, mesial, and incisal wall of a tooth cavity.

axion (ak′se-on)
The brain and spinal cord (cerebrospinal axis).

axio-occlusal (ak′se-o-o-kloo′sal)
Pertaining to the line angle formed by the junction of the axial and occlusal walls of a tooth.

axioplasm (ak′se-o-plazm)
SYN: axoplasm.

axiopodium, pl .axiopodia (ak′se-o-po′de-um, -de-a)
SYN: axopodium.

axiopulpal (ak′se-o-pul′pal)
Referring to the line angle formed by the junction of an axial and pulpal wall of a tooth cavity.

axioversion (ak′se-o-ver′zhun)
Abnormal inclination of the long axis of a tooth.

axipetal (ak-sip′e-tal)
SYN: centripetal (2) . [L. axis + peto, to seek]

axiramificate (ak′se-ram-if′i-kat)
Denoting a nerve cell whose axon, usually short, breaks up into many branches, e.g., Golgi type II cells. [G. axon, axis + grapho, to write]

axis (ax) , pl .axes (ak′sis, ak′sez)
1. [TA] A straight line joining two opposing poles of a spherical body, about which the body may revolve. 2. [TA] The central line of the body or any of its parts. 3. The vertebral column. 4. The central nervous system. 5. [TA] The second cervical vertebra. SYN: vertebra C2&star, epistropheus, odontoid vertebra, second cervical vertebra, toothed vertebra, vertebra dentata. 6. An artery that divides, immediately upon its origin, into a number of branches, e.g., celiac a.. See trunk. [L. axle, a.] basibregmatic a. a line extending from the basion to the bregma. basicranial a. a line drawn from the basion to the midpoint of the sphenoethmoidal suture. basifacial a. a line drawn from the subnasal point to the midpoint of the sphenoethmoidal suture. SYN: facial a.. biauricular a. a straight line joining the two auricles. Cf.:auriculare. celiac a. SYN: celiac (arterial) trunk. cephalocaudal a. SYN: long a. of body. cerebrospinal a. the central nervous system; the brain and spinal cord. SYN: encephalomyelonic a., neural a.. condylar a. a line through the two mandibular condyles around which the mandible may rotate during a part of the opening movement. SYN: condyle cord. conjugate a. SYN: median conjugate. craniofacial a. a straight line passing through the mesethmoid, presphenoid, basisphenoid, and basioccipital bones. electrical a. the net direction of the electromotive forces developed in the heart during its activation, usually represented in the frontal plane. See triaxial reference system. embryonic a. the cephalocaudal a. established in the embryo by the primitive streak. encephalomyelonic a. SYN: cerebrospinal a.. external a. of eye [TA] that part of the optic a. from the midpoint of anterior surface of the cornea to the posterior surface of the posterior pole of the external surface of the sclera. SYN: a. externus bulbi oculi [TA] . a. externus bulbi oculi [TA] SYN: external a. of eye. facial a. SYN: basifacial a.. axes of Fick three axes that pass through the center of the eye vertically (Z), horizontally in the coronal plane (X), and horizontally in the sagittal plane (Y). All ocular rotations can be described by rotation along one of these axes. hinge a. SYN: transverse horizontal a.. instantaneous electrical a. the resultant a. of the electromotive forces developing in the heart at any given moment. internal a. of eye [TA] that part of the optic a. from the midpoint of the posterior surface of the cornea to the anterior surface of the retina opposite the posterior pole. SYN: a. internus bulbi oculi [TA] . a. internus bulbi oculi [TA] SYN: internal a. of eye. a. of lens a line connecting the anterior and posterior poles of the lens of the eye. SYN: a. lentis. a. lentis SYN: a. of lens. long a. a line extending through the center of an object lengthwise; in dentistry, the line extending inciso- (occluso-) cervically parallel to axial surfaces of a tooth. long a. of body the imaginary straight line in the median plane which nearly intersects the center of all transverse planes through the body, running from the apex of the skull through the center of the perineum and continuing between the lower limbs, parallel to and equidistant from the long axes of the limbs; in theory, this is the line about which the body's mass is equally distributed. SEE ALSO: embryonic a.. SYN: cephalocaudal a.. mandibular a. SYN: transverse horizontal a.. mean electrical a. the average magnitude and direction of all the electromotive forces developed during the cardiac event under consideration; e.g., atrial or ventricular depolarization, or ventricular repolarization. SEE ALSO: a. deviation. neural a. SYN: cerebrospinal a.. neutral a. of straight beam the a. perpendicular to the plane of loading of a beam at stresses within the proportional limit; it lies at the gravity a. of the cross-section of the beam. normal electrical a. a mean electrical a. of the heart situated between minus 30° and +90°. See hexaxial reference system. opening a. an imaginary line around which the mandibular condyles may rotate during opening and closing movements. Cf.:fulcrum line. optic a. [TA] the a. of the eye connecting the anterior and posterior poles; it usually diverges from the visual a. by five degrees or more. SYN: a. opticus [TA] . a. opticus [TA] SYN: optic a.. orbital a. the line from the center of the optic foramen (apex of orbit) extending anteriorly, laterally, and inferiorly to the middle of the orbital opening. pelvic a. SYN: a. of pelvis. a. pelvis [TA] SYN: a. of pelvis. a. of pelvis [TA] a hypothetical curved line joining the center point of each of the four planes of the pelvis, marking the center of the pelvic cavity at every level. SYN: a. pelvis [TA] , pelvic a., plane of pelvic canal. principal optic a. a line passing through the center of the lens of a refracting system at right angles to its surface. pupillary a. a line perpendicular to the surface of the cornea, passing through the center of the pupil; the “direction of gaze.” rotational a. SYN: fulcrum line. sagittal a. in dentistry, the line in the frontal plane around which the working side condyle rotates during mandibular movement. secondary a. any ray passing through the optical center of a lens. a. of symmetry an a. through a particle ( e.g., a virus) on such a plane that, if the particle is rotated on the a., there are two or more positions at which the particle appears identical. thoracic a. 1. SYN: thoracoacromial artery. 2. SYN: thoracoacromial vein. thyroid a. SYN: thyrocervical (arterial) trunk. transporionic a. an imaginary line connecting the upper central points of the external auditory meatuses; used in radiographic cephalometry. See porion. transverse horizontal a. an imaginary line around which the mandible may rotate through the horizontal plane. SYN: hinge a., mandibular a.. vertical a. in dentistry, the line around which the working side condyle rotates in the horizontal plane during mandibular movement. visual a. the straight line extending from the object seen, through the center of the pupil, to the macula lutea of the retina. SYN: line of vision. Y-a. a cephalometric indicator of the vertical and horizontal coordinates of mandibular growth expressed in degrees of the inferior facial angle formed by the intersection of the sella-gnathion plane with the Frankfort horizontal plane.

axo-
Axis; axion. [G. axon, axis]

axoaxonic (ak′so-ak-son′ik)
Relating to synaptic contact between the axon of one nerve cell and that of another. See synapse.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

. . . Feedback