Copy of `Dorland's Medical Dictionary`

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Dorland's Medical Dictionary Category: Health and Medicine > Medical Dictionary Date & country: 31/12/2010, USA Words: 39128

asthenic type
a constitutional type marked by a slender body, long neck, long, flat chest and abdomen, and poor muscular development.

asthenocoria
(as″thә-no-kor´e-ә) sluggishness of the pupillary light reflex.

asthenopia
(as″thә-no´pe-ә) weakness or easy fatigue of the eye, with pain in the eyes, headache, and dimness of vision. adj., asthenop´ic., adj. accommodative asthenopia asthenopia due to strain of the ciliary muscle. muscular asthenopia as...

asthenospermia
(as″thә-no-spur´me-ә) reduced motility of spermatozoa in the semen.

asthma
(az´mә) a condition marked by recurrent attacks of dyspnea, with airway inflammation and wheezing due to spasmodic constriction of the bronchi; it is also known as bronchial asthma. Attacks vary greatly from occasional periods of wheezing and slight dyspnea to severe attacks that almost cause suffocation. The most commo...

astigmatism
(ә-stig´mә-tiz-әm) an error of refraction in which a ray of light is not sharply focused on the retina, but is spread over a more or less diffuse area; it is due to differences in curvature in the refractive surfaces (cornea and lens) of the eye. adj., astigmat´ic., adj. ...

astigmatometer
(ә-stig″mә-tom´ә-tәr) an apparatus used in measuring astigmatism.

astigmometer
(as″tig-mom´ә-tәr) astigmatometer.

astomia
(ә-sto´me-ә) congenital atresia of the mouth. adj., asto´matous., adj.

astragalectomy
(as″trag-ә-lek´tә-me) excision of the astragalus.

astragalus
(as-trag´ә-lәs) talus. adj., astrag´alar., adj.

Astrakhan fever
a type of spotted fever observed in the summer in the Russian city of Astrakhan; it may be a variant of boutonneuse fever.

astraphobia
(as″trә-fo´be-ә) irrational fear of thunder and lightning.

astringent
(ә-strin´jәnt) causing contraction or arresting discharges. an agent that causes contraction or arrests discharges, usually locally after topical application. Astringents act as protein precipitants and arrest discharge by causing shrinkage of tissue. Skin preparations such as shaving lotions o...

astroblast
(as´tro-blast) a cell that develops into an astrocyte.

astroblastoma
(as″tro-blas-to´mә) an astrocytoma of Grade II, composed of cells with abundant cytoplasm and two or three nuclei.

astrocyte
(as´tro-sīt) a neuroglial cell characterized by fibrous or protoplasmic processes; collectively called astroglia or macroglia. Astrocyte in association with a blood vessel.

astrocytoma
(as″tro-si-to´mә) a tumor composed of astrocytes; classified in order of malignancy as: Grade I, consisting of fibrillary or protoplasmic astrocytes; Grade II (astroblastoma); and Grades III and IV (glioblastoma multiforme).

astrocytosis
(as″tro-si-to´sis) proliferation of astrocytes owing to the destruction of nearby neurons during a hypoxic or hypoglycemic episode. See also gliosis.

astroglia
(as-trog´le-ә) neuroglia tissue made up of astrocytes.

astrogliosis
(as-trog″le-o´sis) gliosis.

Astroviridae
a family of RNA viruses that cause gastroenteritis in humans and other animals; the single genus is Astrovirus.

Astrovirus
the sole genus of the family Astroviridae, RNA viruses with several different serotypes that cause gastroenteritis in humans and other animals.

asymbolia
(ă-sim-bo´le-ә) loss of ability to understand symbols, such as words, figures, gestures, signs; called also asemasia.

asymmetrical septal hypertrophy
hypertrophic cardiomyopathy. the term is sometimes limited to cases of hypertrophic cardiomyopathy in which the hypertrophy is localized to the interventricular septum. See also hypertrophic obstructive cardiomyopathy.

asymmetry
(a-sim´ә-tre) lack or absence of symmetry; dissimilarity in corresponding parts or organs on opposite sides of the body that are normally alike. In chemistry, lack of symmetry in the special arrangements of the atoms and radicals within the molecule or crystal. adj., asymmet´rical., adj.

asymphytous
(ә-sim´fә-tәs) separate or distinct; not grown together.

asymptomatic
(a″simp-to-mat´ik) showing no symptoms or signs of a disease or disorder.

asymptomatic infection
subclinical infection.

asynchronism
(a-sing´krә-niz-әm) asynchrony.

asynchronous
(a-sing´krә-nәs) pertaining to asynchronism. in cardiac pacing terminology, said of a pacemaker that cannot sense any spontaneous underlying cardiac electrical activity, so that pacing is done at a fixed, constant rate.

asynchronous atrial pacemaker
atrial asynchronous pacemaker.

asynchronous mode
a pacing mode which there is regular stimulation without regard to sensed cardiac signals.

asynchronous pacemaker
an implanted pacemaker that delivers stimuli at a fixed rate, independent of any atrial or ventricular activity; this type is now rarely used except to initiate or terminate some tachycardias.

asynchronous ventricular pacemaker
ventricular asynchronous pacemaker.

asynchrony
(a-sing´krә-ne) the occurrence at distinct times of events normally synchronous; disturbance of coordination; called also asynchronism. adj., asyn´chronous., adj.

asynclitism
(ә-sin´klĭ-tiz-әm) oblique presentation of the fetal head in labor, called anterior asynclitism when the anterior parietal bone is designated the point of presentation, and posterior asynclitism when the posterior parietal bone is so designated. dyserythropoiesis.

asyndesis
(ә-sin´dә-sis) a pattern of language in which words and phrases are juxtaposed without grammatical linkage; seen in schizophrenic and other mental disorders.

asynechia
(a″sin-ek´e-ә) absence of continuity of structure.

asynergia
(a″sin-ur´je-ә) lack of coordination among parts or organs normally acting in unison. adj., asyner´gic., adj.

asynovia
(a″sә-no´ve-ә) absence or insufficiency of synovial secretion.

asyntaxia
(a″sin-tak´se-ә) lack of proper and orderly embryonic development.

asystole
(a-sis´to-le) cardiac standstill or arrest; absence of heartbeat. adj., asystol´ic., adj.

At
astatine.

at no
atomic number.

at wt
atomic weight.

Atabrine
(at´ә-brēn) trademark for a preparation of quinacrine, an anthelmintic and antimalarial agent.

atactic
(ә-tak´tik) pertaining to or characterized by ataxia; marked by incoordination or irregularity.

Atarax
(at´ә-raks) trademark for preparations of hydroxyzine hydrochloride, an antianxiety agent, antiemetic, sedative, and antipruritic.

ataraxia
(at″ә-rak´se-ә) serenity, calmness, peace of mind.

atavism
(at´ә-viz-әm) apparent inheritance of characters from remote ancestors. adj., atavis´tic., adj.

ataxia
(ә-tak´se-ә) failure of muscular coordination; irregularity of muscular action. adj., atac´tic, atax´ic., adj.

ataxia-telangiectasia
a severe, autosomal recessive, progressive ataxia, associated with telangiectasias (dilation of small blood vessels) in the skin and eyes; immunodeficiency with frequent infections of the respiratory tract from sinuses to lungs; and abnormal eye movements. Called also Louis-Bar syndrome.

ataxia-telangiectasia syndrome
ataxia-telangiectasia.

ataxiaphasia
(ә-tak″se-ә-fa´zhә) inability to arrange words into sentences.

ataxic aphasia
expressive aphasia.

ataxic gait
an unsteady, uncoordinated walk, with a wide base and the feet thrown out, coming down first on the heel and then on the toes with a double tap.

ataxophemia
(ә-tak″so-fe´me-ә) dysarthria.

atazanavir
(at″ә-zan´ә-vir) an in inibitor of human immunodeficiency virus-1 (HIV-1) protease, used as the sulfate salt in the treatment of HIV-1 infection.

atelectasis
(at″ә-lek´tә-sis) a collapsed or airless state of the lung, which may be acute or chronic and involving all or only part of a lung. The primary cause is obstruction of the bronchus that serves the affected area. When atelectasis occurs suddenly or acutely, there may be dyspnea, cyanosis, fever, a drop in blo...

atelectatic otitis media
tympanic membrane atelectasis.

atelia
(ә-te´le-ә) imperfect or incomplete development.

atelocardia
(at″ә-lo-kahr´de-ә) imperfect development of the heart.

atelocephaly
(at″ә-lo-sef´ә-le) imperfect development of the skull. adj., atelocephal´ic, ateloceph´alous., adj.

atelomyelia
(at″ә-lo-mi-e´le-ә) imperfect development of the spinal cord.

atenolol
(ә-ten´ә-lol) a cardioselective beta-adrenergic blocking agent used in the treatment of hypertension and chronic angina pectoris and the prevention and treatment of myocardial infarction and cardiac arrhythmias; administered orally or intravenously.

ATG
antithymocyte globulin.

athelia
(ә-the´le-ә) congenital absence of the nipples.

atherectomy
(ath″әr-ek´tә-me) the removal of atherosclerotic plaque from an artery using a rotary cutter inside a special catheter guided radiographically; it does not extend to the tunica intima as endarterectomy does.

atherectomy catheter
a catheter containing a rotating cutter and a collecting chamber for debris, used for atherectomy and endarterectomy; it is inserted percutaneously under radiographic guidance.

athermic
(a-thur´mik) without rise of temperature.

athermosystaltic
(ә-thur″mo-sis-tal´tik) not contracting under the action of cold or heat; said of muscles.

atheroembolus
(ath″әr-o-em´bo-lәs) pl. atheroem´boli an embolus composed of cholesterol or its esters, or of fragments of atheromatous plaques, typically lodging in small arteries.

atherogenesis
(ath″әr-o-jen´ә-sis) formation of abnormal fatty or lipid masses in arterial walls. adj., atherogen´ic., adj.

atheroma
(ath″әr-o´mә) an abnormal mass of fatty or lipid material with a fibrous covering, existing as a discrete, raised plaque within the intima of an artery. adj., atherom´atous., adj.

atheromatosis
(ath″әr-o″mә-to´sis) the presence of multiple atheromas.

atheromatous plaque
fibrous plaque.

atheromatous ulcer
loss of intima over an atheroma, often causing thrombus formation.

atherosclerosis
(ath″әr-o-sklә-ro´sis) a common form of arteriosclerosis in which deposits of yellowing plaques (atheromas) containing cholesterol, other lipoid material, and lipophages are formed on the inner walls of large and medium-sized arteries. adj., atherosclerot´ic., adj.

atherosclerotic aneurysm
arteriosclerotic aneurysm.

athetoid
(ath´ә-toid) resembling athetosis. affected with athetosis.

athetosis
(ath″ә-to´sis) repetitive involuntary, slow, sinuous, writhing movements. Positions of fingers in movements of athetosis.

athlete's foot
(ath´lēts) a fungal infection of the skin of the foot, causing itching and often blisters and cracks, usually between the toes. Causative agents are Candida albicans, Epidermophyton floccosum, and species of Trichophyton, which thrive in warmth and dampness. Called also tinea pedis.

athletic proteinuria
effort proteinuria.

athletic type
a constitutional type marked by broad shoulders, deep chest, flat abdomen, thick neck, and good muscular development.

athrepsia
(ә-threp´se-ә) extreme malnutrition and wasting of subcutaneous tissue and muscle; see also marasmus. adj., athrep´tic., adj.

athymia
(ә-thīm´e-ә) absence of functioning thymus tissue. lack of feeling and emotion, as found in depression and other mental disorders.

athyria
(ә-thi´re-ә) absence of functioning thyroid tissue. hypothyroidism.

Ativan
(at´ĭ-van) trademark for preparations of lorazepam, an antianxiety agent, sedative, and anticonvulsant.

atlantal
(at-lan´tәl) pertaining to the atlas.

atlantooccipital joint
either of two joints, each formed by a superior articular pit of the atlas and a condyle of the occipital bone.

atlas
(at´lәs) the first cervical vertebra, the uppermost bone of the vertebral column, which supports the skull. Atlas. (A), (Top) seen from above; (bottom) seen from the side. (B), Position of the atlas (red), between the occipital bone and the axis.

atloaxoid
(at″lo-ak´soid) pertaining to the atlas and axis.

atm
atmosphere (def. 3).

atmosphere
(at´mәs-fēr) the entire gaseous envelope surrounding the earth and subject to the earth's gravitational field. the air or climate in a particular place. adj., atmospher´ic. a unit of pressure, being that exerted by the earth's atmosphere at sea level; equal to 1.01325 × 105pascals (appro...

atmospheric pressure
the pressure exerted by the atmosphere, usually considered as the downward pressure of air onto a unit of area of the earth's surface; the unit of pressure at sea level is one atmosphere. Pressure decreases with increasing altitude.

atocia
(a-to´shә) sterility in the female.

atom
(at´әm) the smallest particle of an element that has all the properties of the element. adj., atom´ic., adj. There are two main parts of an atom: the nucleus and the electron cloud. The nucleus is made up of protons, which carry a positive electrical charge, and (except in hydrogen) neutrons, which contain one ...

atomic mass unit
(u) (amu) the unit of mass equal to 1/12 the mass of the nuclide of carbon 12. Called also dalton.

atomic nucleus
nucleus (def. 4).