twin
Pronunciation: /twɪn/
noun
- 1one of two children or animals born at the same birth: experiments were carried out using sets of identical twins the twins were approaching their third birthday I thought you must have a double or be a twin
- a person or thing that is exactly like another: there was a bruise on his cheek, a twin to the one on mine
- (the Twins) the zodiacal sign or constellation Gemini.
adjective
- forming, or being one of, a pair born at one birth: she gave birth to twin boys her twin sister
- forming a matching, complementary, or closely connected pair: the twin problems of economic failure and social disintegration
- Botany growing in pairs: twin seed leaves
- (of a bedroom) containing two single beds: we have twin and three-bedded rooms
- (of a crystal) twinned.
verb ( twins, twinning, twinned)
- link (a town or district) with another in a different country or cause (two towns or districts) to be linked, for the purposes of friendship and cultural exchange: the Russian city of Kostroma is twinned with Durham
- link; combine: the company twinned its core business of brewing with that of distilling

Origin:
late Old English twinn 'double', from twi- 'two'; related to Old Norse tvinnr. Current verb senses date from late Middle English