Medical Dictionary

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apperception (ap-er-sep′shun)
1. The final stage of attentive perception in which something is clearly apprehended and thus is relatively prominent in awareness; the full apprehension of any psychic content. 2. The process of referring the perception of ideas to one's own personality. [L. ad, to, + per- cipio, pp. -ceptus, to take wholly, perceive]

apperceptive (ap-er-sep′tiv)
Relating to, involved in, or capable of apperception.

appersonation, appersonification (a-per′so-na′shun, ap-er-son′i-fi-ka′shun)
A delusion in which one assumes the character of another person.

appestat (ap′e-stat)
The mechanism in the brain (possibly in the hypothalamus) concerned with the appetite and control of food intake. [appetite + G. statos, standing]

appetite (ap′e-tit)
A desire or motive derived from a biologic or psychological need for food, water, sex, or affection; a desire or longing to satisfy any conscious physical or mental need. SYN: orexia (2) . [L. ad-peto, pp. -petitus, to seek after, desire]

applanation (ap′lan-a′shun)
In tonometry, the flattening of the cornea by pressure. Intraocular pressure is directly proportional to external pressure, and inversely proportional to the area flattened. SEE ALSO: a. tonometer. [L. ad, toward, + planum, plane]

applanometry (ap-lan-om′e-tre)
Use of an applanation tonometer.

apple oil
SYN: amyl valerate.

appliance (a-pli′ans)
A device used to improve function of a part, or for therapeutic purposes. [fr, O. Fr. aplier, to apply, fr. L. applico, to fold together] craniofacial a. a device used to immobilize and/or reduce mandibular or midfacial fractures. SEE ALSO: fixation. edgewise a. a fixed, multibanded orthodontic a. using an attachment bracket the slot of which receives a rectangular archwire horizontally, which gives precise control of tooth movement in all three planes of space. extraoral fracture a. a device used for extraoral reduction and fixation of maxillary or mandibular fractures, in which pins, clamps, or screws interjoined with metal or acrylic connectors are used to align the fractured segments. SEE ALSO: external pin fixation. Hawley a. SYN: Hawley retainer. intraoral fracture a. a metal or acrylic device attached to the teeth with wire or cement; used to immobilize fractures of the maxilla and mandible. labiolingual a. an orthodontic a. that consists of a maxillary labial arch wire and a mandibular lingual arch wire. light wire a. an orthodontic a. utilizing small gauge labial wires with expansion and contraction loops formed into it and attached to bands fitted to individual teeth; sometimes called Begg light wire differential force technique. obturator a. an a. used to obliterate congenital or acquired defects of the palate and surrounding structures, usually made of acrylic or rubber. orthodontic a. a mechanism for the application of force to the teeth and their supporting tissues to produce changes in the relationship of the teeth and/or the related osseous structures. ribbon arch a. an a. consisting of a rectangular wire inserted into a specially designed bracket attached to the labial and buccal surfaces of the teeth. Roger Anderson pin fixation a. an a. used in extraoral fixation of mandibular fractures and prognathic corrections in which pins placed in the bone segments are joined by metal connecting rods. SEE ALSO: external pin fixation. surgical a. a metal or plastic a. constructed prior to an operation and used to immobilize or support tissue during the postoperative phase. universal a. a combination of the edgewise and ribbon arch a. techniques, affording precise control of individual teeth in all planes of space.

applicand.
Abbreviation for applicandus, to be applied. [L.]

applicator (ap′li-ka-tor)
A slender rod of wood, flexible metal, or synthetic material, at one end of which is attached a pledget of cotton or other substance for making local applications to any accessible surface. [L. ap-plico, to attach to]

apposition (ap-o-zish′un)
1. The placing in contact of two substances. 2. The condition of being placed or fitted together. 3. The relationship of fracture fragments to one another. 4. The process of thickening of the cell wall. [L. ap-pono, pp. -positus, to place at or to] bayonet a. relationship of two fracture fragments that lie next to each other rather than in end-to-end contact.

approach (a-proch′)
1. In psychiatry, a term used to describe how interpersonal relationships are negotiated. 2. The path or method used to expose the operative field during an operation. [M.E., fr. O. Fr., fr L.L. appropio, to come nearer, fr. ad, to + propius, nearer] facial recess a. a surgical a. to the middle ear from the mastoid through the recess lateral to the facial nerve canal. idiographic a. the comprehensive study of an individual as a basis for understanding human behavior in general. infratemporal a. surgical a. to the base of the skull and its contents from inferior to the temporal bone. middle fossa a. surgical a. to the cerebellopontine angle through that portion of the floor of the middle cranial fossa that is the anterior surface of the petrous pyramid of the temporal bone. nomothetic a. a frame of psychologic reference that attempts to provide norms and general principles of behavior by the study of groups. posterior fossa a. surgical a. to the cerebellopontine angle through the mastoid process of the temporal bone. regressive-reconstructive a. a form of psychotherapy in which regression, in order to resurrect some original psychic trauma, is an integral part of the treatment. retrosigmoid a. a surgical a. to the cerebellopontine angle through the occipital bone posterior to the sigmoid sinus. transcochlear a. a surgical a. to the internal auditory canal through the cochlea. translabyrinthine a. surgical a. to the cerebellopontine angle through the inner ear.

approximate (a-prok′si-mat)
To bring close together. In dentistry: 1. Proximate, denoting the contact surfaces, either mesial or distal, of two adjacent teeth. 2. Close together; denoting the teeth in the human jaw, as distinguished from the separated teeth in certain of the lower animals. [L. ad, to, + proximus, nearest]

approximation (a-prok-si-ma′shun)
In surgery, bringing tissue edges into desired apposition for suturing. steady state a. an assumption in the derivation of an enzyme rate expression in which the rate of change of the concentration of any enzyme species is zero or much smaller than d[P]/dt.

APR
Abbreviation for abdominoperineal resection.

apractagnosia (a-prak-tag-no′se-a)
SYN: constructional apraxia. [G. a- priv. + praktea, things to be done, + gnosis, recognition]

apractic (a-prak′tik)
SYN: apraxic.

apragmatism (a-prag′ma-tizm)
An interest in theory or dogmatism rather than in practical results. [G. a- priv. + pragmatism]

apraxia (a-prak′se-a)
1. A disorder of voluntary movement, consisting of impairment in the performance of skilled or purposeful movements, notwithstanding the preservation of comprehension, muscular power, sensibility, and coordination in general; due to acquired cerebral disease. 2. A psychomotor defect in which the proper use of an object can not be carried out although the object can be named and its uses described. [G. a- priv. + pratto, to do] constructional a. a. manifested as an impairment in activity such as building, assembling, and drawings; caused by parietal lobe lesions. SYN: apractagnosia. cortical a. SYN: motor a.. gait a. a. for walking, accompanied by inability to make walking movements with the legs. ideokinetic a., ideomotor a. a form of a. in which simple acts are incapable of being performed, presumably because the connections between the cortical centers that control volition and the motor cortex are interrupted. SYN: transcortical a.. innervation a. SYN: motor a.. limb-kinetic a. SYN: motor a.. motor a. an inability to make movements or to use objects for the purpose intended. SYN: cortical a., innervation a., limb-kinetic a.. ocular motor a. a congenital inability to initiate horizontal saccades. Children with this condition often use head thrusts to move their eyes to the left and right. transcortical a. SYN: ideokinetic a.. verbal a. a speech disorder in which phonemic substitutions are constantly used for the desired syllable or word.

apraxic (a-prak′sik)
Marked by or pertaining to apraxia. SYN: apractic.

apricot kernel oil (a′pri-kot)
See persic oil.

aproctia (a-prok′she-a)
Congenital absence or imperforation of the anus. [G. a- priv. + proktos, anus]

aprofen, aprofene, aprophen (ap′ro-fen, ap′ro-fen, ap′ro-fen)
Analgesic and antispasmodic.

aprosody (a-pros′o-de)
Absence, in speech, of the normal pitch, rhythm, and variations in stress. [G. a- priv. + prosodia, voice modulation]

aprosopia (ap-ro-so′pe-a)
Congenital absence of the greater part or all of the face, usually associated with other malformations. [G. a- priv. + prosopon, face]

aprotinin (a-pro′ti-nin)
A protease and kallikrein inhibitor obtained from animal organs; a polypeptide with a molecular weight of about 6000. May be useful in the treatment of pancreatitis and in preventing bleeding after surgery involving cardiopulmonary bypass.

APS
Abbreviation for adenosine 5′-phosphosulfate.

6-APS
Abbreviation for 6-aminopenicillanic acid.

aPTT
Abbreviation for activated partial thromboplastin time.

APUD
Proposed designation for a group of cells in different organs secreting polypeptide hormones or neurotransmitters. Cells in this group have certain biochemical characteristics in common, the first letters of which form the name: they contain amines, such as catecholamine and 5-hydroxytryptamine, take up precursors of these amines in vivo, and contain amino-acid decarboxylase. [amine precursor uptake, decarboxylase]

apurinic acid (a-pu-rin′ik)
DNA from which the purine bases have been removed by mild acid treatment.

apyknomorphous (a-pik-no-mor′fus)
Denoting a cell or other structure that does not stain deeply because the stainable or chromophil material is not closely aggregated. [G. a- priv. + pyknos, thick, + morphe, shape, form]

apyrase (a-pi′ras)
An enzyme catalyzing hydrolytic removal of two orthophosphate residues from adenosine 5′-triphosphate to yield adenosine 5′-monophosphate; i.e., ATP + 2H2O → AMP + 2Pi. SYN: ADPase, ATP-diphosphatase.

apyretic (a-pi-ret′ik)
SYN: afebrile.

apyrexia (a-pi-rek′se-a)
Absence of fever. [G. a- priv. + pyrexis, fever]

apyrexial (a-pi-rek′se-al)
SYN: afebrile.

apyrimidinic acid (a-pi′rim-i-din′ik)
DNA from which the pyrimidine bases have been removed by chemical treatment ( e.g., exposure to hydrazine).

aq.
Abbreviation for L. aqua, water.

aq. bull.
Abbreviation for L. aqua bulliens, boiling water.

aq. dest.
Abbreviation for L. aqua destillata, distilled water.

aq. ferv.
Abbreviation for L. aqua fervens, hot water.

aq. frig.
Abbreviation for L. aqua frigida, cold water.

aqua, gen. and pl. aquae (ak′wa, ah′kwah)
H2O. Pharmaceutical waters, aquae, are aqueous solutions of volatile substances ( e.g., rose water). Pharmaceutical solutions, liquors, are aqueous solutions of nonvolatile substances. See water (3) , solution (3) . [L.] a. regia, a. regalis SYN: nitrohydrochloric acid. [L. royal water, so called from its power to dissolve gold]

aquacobalamin (ak′wa-ko-bal′a-min)
Vitamin B12a (tautomeric with B12b);a cobalamin derivative in which the sixth coordinate bond of the cobaltic ion is attached to a water molecule. SEE ALSO: vitamin B12. SYN: aquocobalamin.

aquaphobia (ak-wa-fo′be-a)
Morbid fear of water. [L. aqua, water, + G. phobos, fear]

aquapuncture (ak-wa-punk′chur)
Rarely used term for a hypodermic injection of water. [L. aqua, water, + punctura, puncture]

Aquaspirillum (ah-kwah-spi-ril′um)
A genus of motile, nonsporeforming, aerobic bacteria (family Spirillaceae) containing Gram-negative, rigid, helical or helically curved cells that are 0.2–1.5 μm in diameter. Motile cells contain fascicles of flagella at one or both poles. Some species can grow anaerobically with nitrate instead of oxygen as the terminal electron acceptor. These organisms are chemoorganotrophic, possessing a strictly respiratory metabolism. They do not ferment carbohydrates; a few species can oxidize a limited variety of carbohydrates. The habitat of these organisms is fresh water. The type species is A. serpens. [L. aqua, water, + spirillum, coil]

aquatic (a-kwat′ik)
1. Of or pertaining to water. 2. Denoting an organism that lives in water.

aqueduct (ak′we-dukt)
A conduit or canal. SYN: aqueductus. [L. aquaeductus] cerebral a. an ependyma-lined canal in the mesencephalon about 20 mm long, connecting the third to the fourth ventricle. SYN: aqueductus mesencephali [TA] , aqueductus cerebri&star, a. of cerebrum, aqueductus sylvii, iter a tertio ad quartum ventriculum, sylvian a.. a. of cerebrum SYN: cerebral a.. cochlear a. [TA] a fine canal in the temporal bone, opening superior to the tympanic canaliculus, connecting the perilymphatic space of the cochlea with the subarachnoid space. SYN: aqueductus cochleae [TA] , ductus perilymphaticus, perilymphatic duct. Cotunnius a. SYN: vestibular a.. fallopian a. SYN: facial canal. sylvian a. SYN: cerebral a.. vestibular a. [TA] a bony canal running from the vestibule and opening on the posterior surface of the petrous portion of the temporal bone, giving passage to the endolymphatic duct and a small vein. SYN: aqueductus vestibuli [TA] , aqueductus cotunnii, Cotunnius a., Cotunnius canal.

aqueductus (ak-we-duk′tus)
SYN: aqueduct. [L. fr. aqua, water, + ductus, a leading, fr. duco, pp. ductus, to lead] a. cerebri [offalt] cerebral aqueduct. a. cochleae [TA] SYN: cochlear aqueduct. a. cotunnii SYN: vestibular aqueduct. a. fallopii SYN: facial canal. a. mesencephali [TA] SYN: cerebral aqueduct. a. sylvii SYN: cerebral aqueduct. a. vestibuli [TA] [NA] SYN: vestibular aqueduct.

aqueous (ak′we-us, a′kwe-us)
Watery; of, like, or containing water.

aquiparous (a-kwip′er-us)
Secreting or excreting a watery fluid. [L. aqua, water, + pario, to bring forth]

aquocobalamin (ak′wo-ko-bal′a-min)
SYN: aquacobalamin.

aquo-ion (ak′wo-i′on)
A hydrated ion; an ion containing one or more water molecules; e.g., Cu(H2O)42+.

aquosity (a-kwos′i-te)
1. The state of being watery. 2. Moisture.

Ar
Symbol for argon.

Ara
Symbol for arabinose, or its mono- or diradical.

ara-
Prefix for arabinose or arabinosyl.

arab-
Gum arabic; similar gummy substances. [G. Araps, Arabos, an Arab]

araban (a′ra-ban)
A polysaccharide that yields arabinose on hydrolysis; a constituent of some pectins.

arabic (a′ra-bik)
Relating to or derived from various species of Acacia having a gummy or resinous exudate.

arabic acid
SYN: arabin.

arabin (a′ra-bin)
A carbohydrate gum, hydrolyzing to d-arabinose and hexoses, found naturally in union with calcium, potassium, and magnesium ions, when it is called gum arabic. SYN: arabic acid.

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