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Medical Dictionary


ultradolichocephalic (ul-tra-dol-i-ko-se-fal′ik)
Denoting a very long skull, one with a cephalic index of less than 65.

ultrafilter (ul′tra-fil-ter)
A semipermeable membrane (collodion, fish bladder, or filter paper impregnated with gels) used as a filter to separate colloids and large molecules from water and small molecules, which pass through.

ultrafiltration (ul′tra-fil-tra′shun)
Filtration through a semipermeable membrane or any filter that separates colloid solutions from crystalloids or separates particles of different size in a colloid mixture.

ultraligation (ul-tra-li-ga′shun)
Ligation of a blood vessel beyond the point where a branch is given off.

ultramicroscope (ul-tra-mi′kro-skop)
A microscope that utilizes refracted light for visualizing objects not visible with the ordinary microscope when direct light is used.

ultramicroscopic (ul′tra-mi-kro-skop′ik)
SYN: submicroscopic.

ultramicrotome (ul-tra-mi′kro-tom)
A microtome used in cutting sections 0.1 μm thick, or less, for electron microscopy.

ultramicrotomy (ul′tra-mi-krot′o-me)
The cutting of ultrathin sections for electron microscopy by use of an ultramicrotome.

ultrasonic (ul-tra-son′ik)
Relating to energy waves similar to those of sound but of higher frequencies (above 30,000 Hz). [ultra- + L. sonus, sound]

ultrasonics (ul-tra-son′iks)
The science and technology of ultrasound, its characteristics and phenomena.

ultrasonogram (ul-tra-son′o-gram)
The image obtained by ultrasonography. SEE ALSO: echogram. SYN: sonogram.

ultrasonograph (ul′tra-son′o-graf)
Computerized instrument used to create an image using ultrasound. SYN: sonograph. [ultra- + L. sonus, sound, + G. grapho, to write]

ultrasonographer (ul′tra-so-nog′ra-fer)
A person who performs and/or interprets ultrasonographic examinations. SYN: echographer, sonographer.

ultrasonography (ul′tra-so-nog′ra-fe)
The location, measurement, or delineation of deep structures by measuring the reflection or transmission of high frequency or ultrasonic waves. Computer calculation of the distance to the sound-reflecting or absorbing surface plus the known orientation of the sound beam gives a two-dimensional image. SEE ALSO: ultrasound. SYN: echography, sonography. [ultra- + L. sonus, sound, + G. grapho, to write] Doppler u. application of the Doppler effect in ultrasound to detect movement of scatterers (usually red blood cells) by the analysis of the change in frequency of the returning echoes.In many settings, ultrasound has supplanted x-radiography as the imaging method of choice, because it poses no known risk to patients and is noninvasive and of moderate cost. Doppler-created ultrasound makes possible real-time viewing of tissues, blood flow, and organs that cannot be observed by any other method. It is particularly valuable in cardiology and obstetrics. duplex u. the combination of real-time and Doppler u.. endovaginal u. pelvic u. using a probe inserted into the vagina. gray-scale u. the display of the ultrasound echo amplitude or signal intensity as different shades of gray, improving image quality compared to the obsolete black and white presentation. real-time u. rapid serial ultrasound images produced using a phased array or scanning transducer; produces a video display of organ motion, such as heart valve or fetal motion.

ultrasonosurgery (ul′tra-son-o-ser′jer-e)
Use of ultrasound techniques to disrupt cells, tissues, or tracts, particularly in the central nervous system.

ultrasound (ul′tra-sownd)
Sound having a frequency greater than 30,000 Hz. diagnostic u. the use of u. to obtain images for medical diagnostic purposes, employing frequencies ranging from 1.6 to about 10 MHz. obstetric u. use of diagnostic u. during pregnancy.

ultrastructure (ul-tra-struk′choor)
Structures or particles seen with the electron microscope. SYN: fine structure.

ultratherm (ul′tra-therm)
A short-wave diathermy machine. [ultra- + G. therme, heat]

ultraviolet (ul-tra-vi′o-let)
Denoting electromagnetic rays at higher frequency than the violet end of the visible spectrum. u. A (UVA) u. radiation from 320 to 400 nm that causes skin tanning but is very weakly sunburn-producing and carcinogenic. u. B (UVB) u. radiation from 290 to 320 nm that most effectively causes sunburning and tanning; excessive UVB exposure is a cause of cancer of fair skin. u. C u. radiation from 200 to 290 nm; UVC in sunlight does not reach the surface of the earth; germicidal and mercury arc lamps may cause sunburn and photokeratitis. extravital u. having wavelengths of 2900 to 1850 Å. intravital u. having wavelengths of 3900 to 3200 Å.

ultromotivity (ul′tro-mo-tiv′i-te)
Power of spontaneous movement. [L. ultro, beyond, on one's own part + L. motio, movement]

ululation (oo-loo-la′shun)
Rarely used term for the inarticulate crying of emotionally disturbed persons. [L. ululo, pp. -atus, to howl]

Latin form of Greek mythological character. See U. syndrome.

umbilical (um-bil′i-kal)
Relating to the umbilicus. SYN: omphalic.

umbilicate, umbilicated (um-bil′i-kat, -kat-ed)
Of navel shape; pitlike; dimpled. [L. umbilicatus]

umbilication (um-bil-i-ka′shun)
1. A pit or navellike depression. 2. Formation of a depression at the apex of a papule, vesicle, or pustule.

umbilicus, pl .umbilici (um-bil′i-kus, um-bi-li-kus; -i-si, -li′ki)
The pit in the center of the abdominal wall marking the point where the umbilical cord entered in the fetus. SYN: belly button, navel. [L. navel]

umbo, gen. umbonis, pl .umbones (um′bo, -bo-nis, -bo-nes) [TA]
1. [NA] A projecting point of a surface. 2. SYN: u. of tympanic membrane. [L. boss of a shield, a knob] u. membranae tympani [TA] SYN: u. of tympanic membrane. u. of tympanic membrane [TA] the projection on the inner surface of the tympanic membrane at the end of the manubrium of the malleus; this corresponds to the most depressed point of the membrane, viewed laterally, that is commonly called the u.. SYN: u. membranae tympani [TA] , u. (2) [TA] .

Abbreviation for uridine 5′-monophosphate.

UMP synthase
SYN: uridylic acid.

1. Not, akin to L. in- and G. a-, an-. 2. Reversal, removal, release, deprivation. 3. An intensive action. [M.E.]

uncal (ung′kal)
Denoting or relating to the uncus.

unci (un′si)
Plural of uncus.

uncia (un′se-a)
An ounce. [L. a twelfth part, an ounce]

unciform (un′si-form)
SYN: uncinate. [L. uncus, hook, + forma, form]

unciforme (un-si-for′me)
SYN: hamate (bone). [Mod. L. unciform]

Uncinaria (un-si-nar′e-a)
A genus of nematode hookworms that infect various mammals. Species include U. stenocephala, the European hookworm of dogs, cats, and various wild carnivores, also found in North America, where it is much less common than Ancylostoma caninum, though it has been implicated in human cutaneous larva migrans. [LL. uncinus, a hook]

uncinariasis (un′si-na-ri′a-sis)
SYN: ancylostomiasis.

uncinate (un′si-nat)
1. Hooklike or hook-shaped. 2. Relating to an uncus or, specifically, to the u. gyrus (2) or a process of the pancreas or of a vertebra. SYN: unciform. [L. uncinatus]

uncinatum (un-si-na′tum)
SYN: hamate (bone).

uncipressure (un′si-presh-ur)
Arrest of hemorrhage from a cut artery by pressure with a blunt hook. [L. uncus, hook]

uncomplemented (un-kom′ple-men-ted)
Not united with complement and therefore inactive.

unconscious (un-kon′shus)
1. Not conscious. 2. In psychoanalysis, the psychic structure comprising the drives and feelings of which one is unaware. SYN: insensible (1) . collective u. in jungian psychology, the combined engrams or memory potentials inherited from an individual's phylogenetic past.

unconsciousness (un-kon′shus-ness)
An imprecise term for severely impaired awareness of self and the surrounding environment; most often used as a synonym for coma or unresponsiveness.

unco-ossified (un-ko-os′i-fid)
Not co-ossified; not united into one bone.

uncouplers (un-kup′lerz)
Substances such as dinitrophenol that allow oxidation in mitochondria to proceed without the usual concomitant phosphorylation to produce ATP; these poisons thus “uncouple” oxidation and phosphorylation. SYN: uncoupling factors.

uncovertebral (un-ko-ver′te-bral)
Pertaining to or affecting the uncinate process of a vertebra.

unction (ungk′shun)
The action of anointing or rubbing with an ointment or oil. [L. unctio, fr. ungo, pp. unctus, to anoint]

unctuous (ungk′shoo-us, -choo-us)
Greasy or oily. [L. unctuosus, fr. unctio, unction]

uncture (unk′choor)
SYN: ointment.

uncus, pl .unci (un′kus, un′si) [TA]
1. Any hook-shaped process or structure. 2. The anterior, hooked extremity of the parahippocampal gyrus on the basomedial surface of the temporal lobe; the anterior face of the u. corresponds to the olfactory cortex, its ventral surface to the entorhinal area; deep to the u. lies the amygdala (amygdaloid body). SYN: uncinate gyrus, u. gyri parahippocampalis. [L. a hook, fr. G. onkos] u. gyri parahippocampalis SYN: u. (2) .

undecenoic acid (un′des-e-no′ik)
SYN: undecylenic acid.

undecoylium chloride (un-de-ko-il′e-um)
A topical antiseptic.

undecoylium chloride-iodine
A complex of iodine with undecoylium chloride; a cationic detergent used topically as a germicidal agent.

undecylenate (un-des′i-li-nat)
A salt of undecylenic acid.

undecylenic acid (un-des-i-len′ik)
An acid present in small amounts in sweat; used with its zinc salt in ointments, or as a powder in the treatment of fungus diseases of the skin, psoriasis, and certain other cutaneous affections. SYN: undecenoic acid.

underachievement (un′der-a-chev′ment)
Failure to achieve as well as one's abilities would seem to allow.

underachiever (un′der-a-chev′er)
One who manifests underachievement.

underbite (un′der-bit)
A nontechnical term applied to mandibular underdevelopment or to excessive maxillary development.

undercut (un′der-kut)
1. That portion of a tooth that lies between the survey line (height of contour) and the gingivae. 2. The contour of a cross-section of a residual ridge or dental arch which would prevent the insertion of a denture. 3. The contour of a flasking stone which interlocks in such a way as to prevent the separation of the parts.

underdrive pacing (un′der-driv pas′ing)
Electrical stimulation of the heart at a rate lower than that of an existing tachycardia; designed to capture the heart between beats, i.e., to interrupt a reentry pathway in order to terminate the tachycardia.

undernutrition (un′der-noo-tri′shun)
A form of malnutrition resulting from a reduced supply of food or from inability to digest, assimilate, and utilize the necessary nutrients.

undersensing (un′der-sen′sing)
Non-sensing of the intracardiac atrial or ventricular depolarization signal by a pacemaker.

undershoot (un′der-shoot)
A temporary decrease below the final steady-state value that may occur immediately following the removal of an influence that had been raising that value, i.e., overshoot in a negative direction.

understain (un′der-stan)
To stain less deeply than usual.

underventilation (un′der-ven-ti-la′shun)
SYN: hypoventilation.

underwinding (un′der-wind′ing)
The effect of negative supercoiling on a structure of DNA.

undifferentiated (un′dif-er-en′she-a-ted)
Not differentiated; e.g., primitive, embryonic, immature, or having no special structure or function.

undine (un′den, -din)
A small glass flask that was used in irrigation of the conjunctiva. [Mod. L. undina, fr. L. unda, wave]

undiversion (un-di-ver′shun)
Surgical restoration of continuity in any organ system, the flow through which had previously been diverted; e.g., between the upper urinary tract and bladder after supravesical urinary diversion.

undoing (un-doo′ing)
In psychology and psychiatry, an unconscious defense mechanism by which one symbolically acts out in reverse some earlier unacceptable behavior.


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