| twin studies | Methods of detecting genetic aetiology in human traits. The basic premise of twin studies is that monozygotic twins, being formed by the division of a single fertilised ovum, carry identical genes, while dizygotic twins, being formed by the fertilization of two ova by two different spermatozoa, are genetically no more similar than two siblings born after separate pregnancies. (12 Dec 1998) |
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| twin study | A method of detecting genetic causes in human traits and genetic factors in behaviour using sets of twins. (12 Dec 1998) |
| twin-twin transfusion | Direct vascular anastomosis, arterial or venous, between the placental circulations of twins. (05 Mar 2000) |
| twine | 1. To mutually twist together; to become mutually involved. 2. To wind; to bend; to make turns; to meander. "As rivers, though they bend and twine, Still to the sea their course incline." (Swift) 3. To turn round; to revolve. 4. To ascend in spiral lines about a support; to climb spirally; as, many plants twine. Source: Websters Dictionary (01 Mar 1998) |
| twiner | <botany> Any plant which twines about a support. Source: Websters Dictionary (01 Mar 1998) |
| twinge | A sudden momentary sharp pain. (05 Mar 2000) |
| twining | Winding around something; twisting; embracing; climbing by winding about a support; as, the hop is a twinning plant. <botany> The act of one who, or that which, twines; the act of climbing spirally. Source: Websters Dictionary (01 Mar 1998) |
| twink | 1. A wink; a twinkling. 2. <zoology> The chaffinch. Source: Websters Dictionary (01 Mar 1998) |
| twinleaf | <botany> See Jeffersonia. Source: Websters Dictionary (01 Mar 1998) |
| twinned | <chemistry> Composed of parts united according to a law of twinning. See Twin. Source: Websters Dictionary (01 Mar 1998) |
| twinning | <chemistry> The assemblage of two or more crystals, or parts of crystals, in reversed position with reference to each other in accordance with some definite law; also, rarely, in artificial twinning (accomplished for example by pressure), the process by which this reversal is brought about. Polysynthetic twinning, repeated twinning of crystal lamellae, as that of the triclinic feldspars. Repeated twinning, twinning of more than two crystals, or parts of crystals. Twinning axis, Twinning plane. See the Note under Twin. Source: Websters Dictionary (01 Mar 1998) |
| twins, dizygotic | Two offspring produced in the same pregnancy from separate ova fertilised at the same time. (12 Dec 1998) |
| twins, monozygotic | Two offspring developed from one fertilised ovum. (12 Dec 1998) |
| twirl on | <dentistry> A device used to help place ligating modules on brackets. (08 Jan 1998) |
| twist | 1. The act of twisting; a contortion; a flexure; a convolution; a bending. "Not the least turn or twist in the fibres of any one animal which does not render them more proper for that particular animal's way of life than any other cast or texture." (Addison) 2. The form given in twisting. "[He] shrunk at first sight of it; he found fault with the length, the thickness, and the twist." (Arbuthnot) 3. That which is formed by twisting, convoluting, or uniting parts. Specifically: A cord, thread, or anything flexible, formed by winding strands or separate things round each other. A kind of closely twisted, strong sewing silk, used by tailors, saddlers, and the like. A kind of cotton yarn, of several varieties. A roll of twisted dough, baked. A little twisted roll of tobacco. One of the threads of a warp, usually more tightly twisted than the filling. A material for gun barrels, consisting of iron and steel twisted and welded together; as, Damascus twist. The spiral course of the rifling of a gun barrel or a cannon. A beverage made of brandy and gin. 4. [OE.; so called as being a two-forked branch. See Twist] A twig. Gain twist, or Gaining twist, a twist of which the spiral course has an equal pitch throughout. Source: Websters Dictionary (01 Mar 1998) |