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”

Explanation

When mammals have two babies at once, each of them is a twin. If you have a twin brother or sister, the two of you are always the same age. There are identical twins, who have the same DNA, and fraternal twins, who are more like two siblings who happen to be born at the same time. It's more common to describe humans as twins than other animals. The adjective twin can also describe a pair of things, like the twin chocolate cakes you serve at your birthday party or the "Twin Cities" in Minnesota, Minneapolis and St. Paul.

Example Sentences

Dern, who won an Oscar in 2020 for Marriage Story, is also known for films such as Blue Velvet, Jurassic Park and Wild, and TV shows including Big Little Lies and Twin Peaks: The Return.

From BBC • Apr. 29, 2026

Its obesity and weight management support includes offerings from Aaptiv, Berry Street, Curai Health, MyCare by Twin Health, and Wheel that feature dietary and GLP-1 solutions.

From Barron's • Apr. 16, 2026

But immigration agents continued to roam the Twin Cities, and activists continued to get arrested.

From Salon • Apr. 15, 2026

Twin Cities’ hospitality and tourism firms reported that even “legal, foreign-born workers were choosing not to work due to safety concerns.”

From The Wall Street Journal • Mar. 25, 2026

There is exactly one furnished studio apartment listed for the entire Twin Cities area, and they’re not answering the phone on the weekend.

From "Nickel and Dimed: On (Not) Getting By in America" by Barbara Ehrenreich

Related Words

• Siamese twin
• fraternal twin
• identical twin