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Medical Dictionary


One of the finer terminal branches of an artery; a small branch or small ramus. [A.S.]

twilight (twi′lit)
1. Figuratively, a faint light. 2. Pertaining to faint or indistinct mental perception, as in t. state. [A.S. twi-, two]

1. One of two children born at one birth. 2. Double; growing in pairs. [A.S. getwin, double] allantoidoangiopagous twins unequal monochorial twins with fusion of their allantoic vessels within the placenta; the lesser t. is essentially a parasite on the placental circulation of the larger t.. conjoined twins monozygotic twins with varying extent of union and different degrees of residual duplication. The various types of union are named by the use of a prefix designating the region that is united and adding the suffix -pagus, meaning joined ( e.g., craniopagus, thoracopagus); the various types of residual duplication are named by designating the parts duplicated and adding the suffix -didymus, or -dymus, meaning t. ( e.g., cephalodidymus, cephalodymus). conjoined asymmetric twins SYN: conjoined unequal twins. conjoined equal twins conjoined twins in which both members are approximately of the same size, and nearly normal except for the areas of union. SYN: conjoined symmetric twins. conjoined symmetric twins SYN: conjoined equal twins. conjoined unequal twins conjoined twins in which one member is nearly normal (host or autosite) and the other (parasite) is small, incomplete, and dependent for its nutrition upon the more nearly normal member. SYN: conjoined asymmetric twins. dichorial twins SYN: dizygotic twins. diovular twins SYN: dizygotic twins. dizygotic twins twins derived from two separate zygotes. SYN: dichorial twins, diovular twins, fraternal twins, heterologous twins. enzygotic twins SYN: monozygotic twins. fraternal twins SYN: dizygotic twins. heterologous twins SYN: dizygotic twins. identical twins SYN: monozygotic twins. incomplete conjoined twins conjoined twins, the two components of which equal one another but are less than entire individuals. locked twins a form of malpresentation in which a breech t. and a vertex t. become locked at the chin during labor and attempted delivery. monoamniotic twins twins within a common amnion; such t.'s are monovular in origin and may be conjoined. monochorial twins SYN: monozygotic twins. monovular twins SYN: monozygotic twins. monozygotic twins twins resulting from a single fertilized ovum that at an early stage of development becomes separated into independently growing cell aggregations giving rise to two individuals of the same sex and identical genetic constitution. SYN: enzygotic twins, identical twins, monochorial twins, monovular twins, uniovular twins. parasitic t. the smaller of unequal conjoined twins. placental parasitic t. SYN: omphalosite. polyzygotic twins twins resulting from fertilization of more than two ova discharged in a single ovulating cycle. Siamese twins originally, a much publicized conjoined pair of twins (xiphopagus) from Siam in the 19th century; this term has since come into general lay usage for any type of conjoined twins, but is incorrect. uniovular twins SYN: monozygotic twins.

twinge (twinj)
A sudden momentary sharp pain.

Production of equivalent structures by division; the tendency of divided parts to assume symmetric relations.

1. To jerk spasmodically. 2. A momentary spasmodic contraction of a muscle fiber. [A.S. twiccian]

Frederick W., British bacteriologist, 1877–1950. See T. phenomenon, T.-d'Herelle phenomenon.

Abbreviation for individual thromboxanes, designated by capital letters with subscripts indicating structural features.

tybamate (ti′ba-mat)
A tranquilizer related to meprobamate.

tylectomy (ti-lek′to-me)
Surgical removal of a localized swelling or tumor. SEE ALSO: lumpectomy. [G. tyle, lump, + ektome, excision]

tylion, pl .tylia (til′e-on, -le-a; ti′le-on)
A craniometric point at the middle of the anterior edge of the chiasmatic groove. [G. a small pin, dim. of tyle, a lump]

tyloma (ti-lo′ma)
SYN: callosity. [G. a callus] t. conjunctivae localized keratinization of the conjunctiva, occurring in xerosis of the conjunctiva.

tylosis, pl .tyloses (ti-lo′sis, -sez)
Formation of a callus (tyloma). [G. a becoming callous] t. ciliaris SYN: pachyblepharon. t. linguae leukoplakia of the tongue. t. palmaris et plantaris SYN: palmoplantar keratoderma.

tyloxapol (ti-lok′sa-pol)
A detergent and mucolytic agent used as an aerosol to liquify sputum.

tymazoline (ti-maz′o-len)
A nasal decongestant.

See tympano-.

tympanal (tim′pa-nal)
1. SYN: tympanic (1) . 2. Resonant. 3. SYN: tympanitic (2) .

tympanectomy (tim′pa-nek′to-me)
Excision of the tympanic membrane. [tympan- + G. ektome, excision]

tympania (tim-pan′e-a)
SYN: tympanites.

tympanic (tim-pan′ik)
1. Relating to the t. cavity or membrane. SYN: tympanal (1) . 2. Resonant. 3. SYN: tympanitic (2) .

tympanichord (tim-pan′i-kord)
SYN: chorda tympani.

tympanichordal (tim-pan-i-kor′dal)
Relating to the chorda tympani nerve.

tympanicity (tim′pa-nis′i-te)
The quality of being tympanic or drumlike in tone.

tympanism (tim′pa-nizm)
SYN: tympanites.

tympanites (tim-pa-ni′tez)
Swelling of the abdomen from gas in the intestinal or peritoneal cavity. SYN: meteorism, tympania, tympanism. [L. fr. G. t., an edema in which the belly is stretched like a drum, tympanon] uterine t. SYN: physometra.

tympanitic (tim-pa-nit′ik)
1. Referring to tympanites. SYN: tympanous. 2. Denoting the quality of sound elicited by percussing over the inflated intestine or a large pulmonary cavity. SYN: tympanal (3) , tympanic (3) .

tympanitis (tim-pa-ni′tis)
SYN: myringitis.

tympano-, tympan-, tympani-
Tympanum, tympanites. [G. tympanon, drum]

tympanocentesis (tim′pa-no-sen-te′sis)
Puncture of the tympanic membrane with a needle to aspirate middle ear fluid. [tympano- + G. kentesis, puncture]

tympanoeustachian (tim′pa-no-oo-sta′shun, -sta′ke-an)
Relating to the tympanic cavity and the auditory tube.

tympanogram (tim′pah-no-gram)
The printout of an impedance bridge showing the stiffness or the compliance of the middle ear structures as it varies with changes in pressure within the external ear canal.

tympanohyal (tim′pa-no-hi′al)
Pertaining to the relationship between the tympanic cavity and the hyoid arch.

tympanomalleal (tim′pa-no-mal′e-al)
Relating to the tympanic membrane and the malleus.

tympanomandibular (tim′pa-no-man-dib′u-lar)
Relating to the tympanic cavity and the mandible.

tympanomastoid (tim′pa-no-mas′toyd)
Relating to the tympanic cavity and the mastoid process.

SYN: radical mastoidectomy.

tympanomastoiditis (tim′pa-no-mas-toy-di′tis)
Inflammation of the middle ear and the mastoid cells.

tympanometry (tim-pan-om′et-re)
A technique that measures compliance of the tympanic membrane at various levels of air pressure; helpful in diagnosing middle ear effusion, eustachian tube function, and otitis media.

tympanophonia, tympanophony (tim′pa-no-fo′ne-a, tim′pa-nof′o-ne)
SYN: autophony. [tympano- + G. phone, sound]

tympanoplasty (tim′pa-no-plas-te)
Operative correction of a damaged middle ear. [tympano- + G. plasso, to form]

tympanosclerosis (tim′pan-o-skler-o′sis)
The formation of dense connective tissue in the middle ear, often resulting in hearing loss when the ossicles are involved.

tympanosquamosal (tim′pa-no-skwa-mo′sal)
Relating to the tympanic and squamous parts of the temporal bone. SYN: squamotympanic.

tympanostapedial (tim′pa-no-sta-pe′de-al)
Relating to the tympanic cavity and the stapes.

tympanostomy (tim-pan-os′to-me)
An operation to make an opening in the tympanic membrane. SEE ALSO: myringotomy. [tympano- + G. ostium, mouth]

tympanotemporal (tim′pa-no-tem′po-ral)
Relating to the tympanic cavity and the temporal region or bone.

tympanotomy (tim′pa-not′o-me)
SYN: myringotomy. [tympano- + G. tome, incision]

tympanous (tim′pa-nus)
SYN: tympanitic (1) .

tympanum, pl .tympanatympanums (tim′pa-num, tim′pa-na)
SYN: eardrum. [L., fr. G. tympanon, a drum]

tympany (tim′pa-ne)
A low-pitched, resonant, drumlike note obtained by percussing the surface of a large air-containing space, such as the distended abdomen or the thorax with or without pneumothorax. SYN: tympanitic resonance. Skoda t. SYN: skodaic resonance.

John, English physicist, 1820–1893. See T. effect, tyndallization, T. phenomenon.

tyndallization (tin′dal-i-za′shun)
SYN: fractional sterilization. [John Tyndall]

type (tip)
1. The usual form, or a composite form, that all others of the class resemble more or less closely; a model, denoting especially a disease or a symptom complex giving the stamp or characteristic to a class. SEE ALSO: constitution, habitus, personality. 2. In chemistry, a substance in which the arrangement of the atoms in a molecule may be taken as representative of other substances in that class. 3. A specific variation of a structure. SYN: typus, variation (2) . [G. typos, a mark, a model] ampullary t. of renal pelvis [TA] saclike form of renal pelvis in which the calyces open onto a common dilated pelvis. SYN: typus ampullaris pelvis renalis [TA] . basic personality t. 1. an individual's unique, covert, or underlying personality propensities, whether or not they are behaviorally manifest or overt; 2. personality characteristics of an individual which are also shared by a majority of the members of a social group. blood t. blood t.. branching t. of renal pelvis [TA] form of renal pelvis in which no common, expanded, saclike pelvis occurs; rather the major calyces merely merge to form the ureter. SYN: typus dendriticus pelvis renalis [TA] . buffalo t. term used to describe the distribution of a fat deposit seen posteriorly over the upper thoracic spine; seen in hyperadrenocorticalism (Cushing syndrome). SYN: buffalo hump. nomenclatural t. the constituent element of a taxon to which the name of the taxon is permanently attached; the t. of a species is preferably a strain (in special cases it may be a description, a preserved specimen or preparation, or an illustration); the t. of a genus is a species; and the t. of an order, family, or tribe is the genus on whose name the name of the higher taxon is based. test t. test types. wild t. a gene, phenotype, or genotype that is overwhelmingly common among those possible at a locus of interest that it represents the standard characteristic, and therefore presumably not harmful.

typhinia (ti-fin′e-a)
SYN: relapsing fever. [G. typhos, smoke, stupor arising from fever]

See typhlo-.

typhlectasis (tif-lek′ta-sis)
Dilation of the cecum. [G. typhlon, cecum, + ektasis, a stretching out]

typhlectomy (tif-lek′to-me)
SYN: cecectomy.

typhlenteritis (tif′len-ter-i′tis)
SYN: cecitis.

typhlitis (tif′li′tis)
SYN: cecitis.

typhlo-, typhl-
1. The cecum. SEE ALSO: ceco-. [G. cecum] 2. Blindness. [G. typhlos, blind]

typhlodicliditis (tif-lo-dik-li-di′tis)
Inflammation of the ileocecal valve. [G. typhlon, cecum, + diklis (diklid-), double-folding (of doors), + -itis, inflammation]

typhloempyema (tif′lo-em-pi-e′ma)
Presence of an abscess following typhlitis. [G. typhlon, cecum, + empyema, abscess]

typhloenteritis (tif′lo-en-ter-i′tis)
SYN: cecitis.

typhlolithiasis (tif′lo-li-thi′a-sis)
Presence of fecal concretions in the cecum. [G. typhlon, cecum, + lithos, stone]

typhlomegaly (tif′lo-meg′a-le)
Old term for enlargement of the cecum. [G. typhlon, cecum, + megas (megal-), large]

typhlon (tif′lon)
SYN: cecum (1) . [G.]

typhlopexy, typhlopexia (tif′lo-pek-se, tif-lo-pek′se-a)
SYN: cecopexy.

typhlorrhaphy (tif-lor′a-fe)
SYN: cecorrhaphy.


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