n., adj., & v.
n. 1 each of a closely related or associated pair, esp. of children or animals born at a birth. 2 the exact counterpart of a person or thing. 3 a compound crystal one part of which is in a reversed position with reference to the other. 4 (the Twins) the zodiacal sign or constellation Gemini.
adj. 1 forming, or being one of, such a pair (twin brothers). 2 Bot. growing in pairs. 3 consisting of two closely connected and similar parts.
v. (twinned, twinning) 1 tr. & intr. a join intimately together. b (foll. by with) pair. 2 intr. bear twins. 3 intr. grow as a twin crystal. 4 intr. & tr. Brit. link or cause (a town) to link with one in a different country, for the purposes of friendship and cultural exchange. twin bed each of a pair of single beds. twin-engined having two engines. twin-screw (of a ship) having two propellers on separate shafts with opposite twists. twin set esp. Brit. a woman's matching cardigan and jumper. twin town Brit. a town which is twinned with another. twinning n.
[ OE twinn double, f. twi- two: cf. ON tvinnr ]