twin

¹ American  

[twin] / twɪn /

noun

1. 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. twin bed.

4. Also called twin room.  a type of hotel accommodation with twin beds, for occupancy by two persons.

5. Also called hemitrope.  Crystallography. 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.

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adjective

1. being a twin or twins.

   twin sisters.

2. being two persons or things closely related to or closely resembling each other.

3. being one of a pair; identical.

   a twin bracelet; a twin peak.

4. consisting of two similar parts or elements joined or connected.

   a twin vase.

5. Botany, Zoology. occurring in pairs; didymous.

6. Crystallography. of the nature of a twin; hemitrope.

7. twofold or double.

verb (used with object)

twinned, twinning

1. to bring together in close relationship; pair; couple.

2. to furnish a counterpart to or a replica of; match.

3. Informal. to divide or convert into two, parts, similar items, etc..

   The old movie palace will be twinned, making two smaller theaters.

4. Informal. to link or combine with.

   The new grocery store is twinned with a restaurant.

5. Crystallography. to form into a twin.

6. Obsolete. to give birth to as twins.

verb (used without object)

twinned, twinning

1. to give birth to twins.

2. to be paired or coupled.

3. to match or resemble someone or something in a specific way, and to acknowledge this resemblance: Check out these photos of moms and daughters twinning!

   They are twinning so hard right now.

   Check out these photos of moms and daughters twinning!

twin ² American  

[twin] / twɪn /

verb (used with or without object)

Scot.

twinned, twinning

1. twine.

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twin British  

/ twɪn /

noun

1. 1. either of two persons or animals conceived at the same time

   2. ( as modifier ) See also identical fraternal

      a twin brother

2. 1. either of two persons or things that are identical or very similar; counterpart

   2. ( as modifier )

      twin carburettors

3. Also called: macle.  a crystal consisting of two parts each of which has a definite orientation to the other

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verb

1. to pair or be paired together; couple

2. (intr) to bear twins

3. (intr) (of a crystal) to form into a twin

4. archaic (intr) to be born as a twin

5. (tr)

   1. to create a reciprocal relation between (two towns in different countries); pair (a town) with another in a different country

   2. (intr) (of a town) to be paired with a town in a different country

twin Scientific  

/ twĭn /

1. One of two offspring born of a single gestation. Identical twins result from the division of a fertilized egg. Fraternal twins result from the fertilization of two separate eggs at the same time.

2. A crystal structure consisting of two intergrown crystals that are mirror images of each other. Mineral twins can form as result of defective crystal growth in response to stress from rock deformation or during magma cooling.

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Other Word Forms

• twinning noun

Etymology

Origin of twin

First recorded before 900; Middle English adjective twynne, twinne, Old English adjective twinn “twofold, double”; noun and adjective getwinn “double,” (plural getwinnas “twins”); akin to Old Frisian twīna, twīne “two together,” Old Norse tvinnr “double,” Gothic twaihnái “two each”

Example Sentences

“They were sisters,” Hannah says about the twin tables.

From Los Angeles Times • Apr. 8, 2026

Barshay’s twin brother Lawrence is also a corporate lawyer, at rival firm Fried Frank.

From The Wall Street Journal • Apr. 6, 2026

You may have heard about last week’s twin verdicts against Meta and YouTube, which held the tech companies liable for harms their products inflicted on young people.

From Slate • Mar. 30, 2026

Coulson's mum and twin sister Kirsten were among family members in court as the two men were sentenced.

From BBC • Mar. 26, 2026

Velia looked at her twin sister for validation, not grasping the full meaning of what I was getting at.

From "Summer of the Mariposas" by Guadalupe García McCall

Related Words

• Siamese twin
• fraternal twin
• identical twin