Twin  —n. 1 each of a closely related or associated pair, esp. Of children or animals born at a birth. 2 exact counterpart of a person or thing. 3 (the twins) zodiacal sign or constellation gemini. —adj. Forming, or being one of, such a pair (twin brothers). —v. (-nn-) 1 a join intimately together. B (foll. By with) pair. 2 bear twins. 3 link (a town) with one in a different country, for friendship and cultural exchange.  twinning n. [old english: related to *two]