2. Being one of a pair much resembling one another; standing
the relation of a twin to something else; -- often
followed by to or with. --Shak.
3. (Bot.) Double; consisting of two similar and corresponding
parts.
4. (Crystallog.) Composed of parts united according to some
definite law of twinning. See {Twin}, n., 4.
{Twin boat}, or {Twin ship} (Naut.), a vessel whose deck and
upper works rest on two parallel hulls.
{Twin crystal}. See {Twin}, n., 4.
{Twin flower} (Bot.), a delicate evergreen plant ({Linn[ae]a
borealis}) of northern climates, which has pretty,
fragrant, pendulous flowers borne in pairs on a slender
stalk.
{Twin-screw steamer}, a steam vessel propelled by two screws,
one on either side of the plane of the keel.
2. To be born at the same birth. --Shak.
Still we moved Together, twinned, as horse's ear and
eye. --Tennyson.
2. To separate into two parts; to part; to divide; hence, to
remove; also, to strip; to rob. [Obs.]
The life out of her body for to twin. --Chaucer.
2. pl. (Astron.) A sign and constellation of the zodiac;
Gemini. See {Gemini}.
3. A person or thing that closely resembles another.
4. (Crystallog.) A compound crystal composed of two or more
crystals, or parts of crystals, in reversed position with
reference to each other.
Note: The relative position of the parts of a twin may be
explained by supposing one part to be revolved 180[deg]
about a certain axis (called the twinning axis), this
axis being normal to a plane (called the twinning
plane) which is usually one of the fundamental planes
of the crystal. This revolution brings the two parts
into parallel position, or vice versa. A contact twin
is one in which the parts are united by a plane
surface, called the composition face, which is usually
the same as the twinning plane. A penetration twin is
one in which the parts interpenetrate each other, often
very irregularly. Twins are also called, according to
form, cruciform, geniculated, etc.