Twin, either of two young who are simultaneously born from one mother. Twinning, common in many animals, is of two biological kinds: the one-egg (monozygotic), or identical, type and the two-egg (dizygotic), or fraternal, type. 1.

Understanding the Context

Being two or one of two offspring born at the same birth: twin sisters. 2. Being two or one of two identical or similar people, animals, or things: twin cities; a twin bed. 3.

Key Insights

Botany Of or relating to structures, such as flowers, that occur in pairs. 4. Consisting of two identical or similar parts: a twin lamp fixture.