twin

UK: /ˈtwɪn/ US: /twɪn/ ,(twin)

Inflections of 'twin' (v): (⇒ conjugate)

twins

v 3rd person singular

twinning

v pres p

twinned

v past

twinned

v past p

WordReference Random House Learner's Dictionary of American English © 2025

twin¹ /twɪn/   n. [countable]

1. Developmental Biology either of two offspring born at one birth:
   fraternal twins or identical twins.
2. either of two persons or things closely resembling each other.

adj. [before a noun]

3. being a twin or twins:
   twin sisters.
4. being two persons or things closely related to each other.
5. being one of a pair;
   identical:
   twin towers.
6. made of two similar parts connected:
   a twin vase.

WordReference Random House Unabridged Dictionary of American English © 2025

twin¹ (twin),  n., adj., v., twinned, twin•ning. 

n. 

1. Developmental Biology either of two children or animals brought forth at a birth.
2. either of two persons or things closely related to or closely resembling each other.
3. Furniture See twin bed. 
4. Also called twin room. a type of hotel accommodation with twin beds, for occupancy by two persons. Cf. double (def. 13).
5. Crystallography Also called hemitrope. a compound crystal consisting of two or more parts or crystals definitely oriented each to the other;
   macle.
6. Astronomy, Astrology Twins, the constellation or sign of Gemini.

adj. 

7. being a twin or twins:
   twin sisters.
8. being two persons or things closely related to or closely resembling each other.
9. being one of a pair;
   identical:
   a twin bracelet; a twin peak.
10. consisting of two similar parts or elements joined or connected:
    a twin vase.
11. Botany, Zoology occurring in pairs;
    didymous.
12. Crystallography of the nature of a twin;
    hemitrope.
13. twofold or double.

v.t. 

14. to bring together in close relationship;
    pair;
    couple.
15. to furnish a counterpart to or a replica of;
    match.
16. Informal Terms to divide or convert into two, parts, similar items, etc.:
    The old movie palace will be twinned, making two smaller theaters.
17. Informal Terms to link or combine with:
    The new grocery store is twinned with a restaurant.
18. Crystallography to form into a twin.
19. [Obs.] to give birth to as twins.

v.i. 

20. to give birth to twins.
21. to be paired or coupled.

• bef. 900; Middle English; Old English twinn (adjective, adjectival), getwinn (noun, nominal and adjective, adjectival); akin to Old Frisian twīne, Old Norse tvinnr double, Gothic twaihnai

twin² (twin), v.t., v.i., twinned, twin•ning. [Scot.]

1. Scottish Terms twine².

Collins Concise English Dictionary © HarperCollins Publishers::

twin / twɪn/ noun

1. either of two persons or animals conceived at the same time
2. (as modifier): a twin brother
   See also identical3, fraternal3
3. either of two persons or things that are identical or very similar; counterpart
4. (as modifier): twin carburettors
5. Also called: macle a crystal consisting of two parts each of which has a definite orientation to the other

verb (twins, twinning, twinned)

1. to pair or be paired together; couple
2. (intransitive) to bear twins
3. (intransitive) (of a crystal) to form into a twin
4. (transitive) to create a reciprocal relation between (two towns in different countries); pair (a town) with another in a different country
5. (intransitive) (of a town) to be paired with a town in a different country

Etymology: Old English twinn; related to Old High German zwiniling twin, Old Norse tvinnr double

ˈtwinning noun