What does twin mean?
A twin is, most commonly, one of two people born at the same time, especially a brother or sister. The word can also describe a person, object, place, or phenomenon that closely resembles another, as in “a twin of the original building” or “twin peaks.” In this extended sense, twin suggests a striking similarity or a deliberate pairing, whether natural or manufactured. Adjectival uses often appear in familiar compounds such as “twin brother,” “twin sister,” and “twin towers.” The verb “twin” is less common but can mean to match something with a counterpart, especially in institutional or civic relationships, as in “the university is twinned with a college abroad.” The word’s history is unusually simple: it descends from an Old English form meaning “two,” which was gradually applied to people and things that occur in pairs. Today, “twin” remains useful because it captures both close resemblance and the idea of a paired counterpart.
One of two people born at the same time, especially a sibling; also a person or thing that closely resembles another.
"Her twin is the lead singer in a band from another city."
The familial sense is most common. In extended uses, “twin” often implies a particularly close or striking match.
Closely resembling another or forming a matched pair.
"The lighthouse and the nearby building are near-perfect twins."
Frequently used attributively in compounds such as “twin brother,” “twin sister,” “twin towers,” and “twin peaks.”
To pair something with a closely corresponding counterpart, or to form such a pairing.
"The two universities are twinned under a longstanding exchange agreement."
This is less common than the noun and adjective. The passive construction “twinned with” is especially frequent in civic, educational, and institutional contexts.
The plural is used for two or more people born at the same time and for multiple matching people or things.
"The twins study different subjects but remain close friends."
The word twin began as an Old English numeral meaning “two,” before it came to describe paired people, objects, and places.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does twin come from?
The word comes from Old English twȳn, originally a numeral meaning “two,” from a Germanic root related to words such as two, twelve, and twenty. Its use for children born at the same time and for closely matching things developed from this earlier sense of a pair. The modern pronunciation reflects the usual unstressed vowel of the English word and is shared across both British and American English.
Related word forms
How twin is actually used
The word is common in both formal and informal English. It is especially frequent in family, biographical, geographical, and architectural contexts. As a verb, “twin” is relatively uncommon and is often used in the passive form “twinned with,” particularly for cities, institutions, or organizations.
Easily confused with twin
A twin is a closely matching person or thing, while twine is a strong cord or string used for tying things together.