1. One of two offspring born at the same birth.
2. One of two identical or similar people, animals, or things; a counterpart.
3. twins Mineralogy Two interwoven crystals that are mirror images of each other.
4. A twin bed.
1. 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. 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.
5. Being of a size that will fit a twin bed: twin sheets.
v. twinned, twin·ning, twins
a. To give birth to twins.
b. Archaic To be one of twin offspring.
2. To be paired or coupled.
1. To pair or couple.
2. To provide a match or counterpart to.
[Middle English, from Old English twinn, twofold; see dwo- in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.
American Heritage Dictionary Products
The American Heritage Dictionary, 5th Edition
The American Heritage Dictionary of Idioms
The American Heritage Roget's Thesaurus
Curious George's Dictionary
The American Heritage Children's Dictionary
The American Heritage Dictionary of Indo-European Roots
The American Heritage Student Grammar Dictionary
The American Heritage Desk Dictionary + Thesaurus
The American Heritage Science Dictionary
The American Heritage Dictionary of Business Terms
The American Heritage Student Dictionary
The American Heritage Essential Student Thesaurus