Twin

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.
Compare double (def 13).
5.
Also called hemitrope. Crystallography. a compound crystal consisting of two or more parts or crystals definitely oriented each to the other; macle.
6.
Twins, Astronomy, Astrology. the constellation or sign of Gemini.
adjective
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.
verb (used with object), twinned, twinning.
14.
to bring together in close relationship; pair; couple.
15.
to furnish a counterpart to or a replica of; match.
16.
Informal. to divide or convert into two, parts, similar items, etc.:
The old movie palace will be twinned, making two smaller theaters.
17.
Informal. to link or combine with:
The new grocery store is twinned with a restaurant.
18.
Crystallography. to form into a twin.
19.
Obsolete. to give birth to as twins.
verb (used without object), twinned, twinning.
20.
to give birth to twins.
21.
to be paired or coupled.
verb (used with or without object), twinned, twinning. Scot.
1.
twine2 .
noun
1.

either of two persons or animals conceived at the same time
(as modifier): a twin brother See also identical (sense 3), fraternal (sense 3)

2.

either of two persons or things that are identical or very similar; counterpart
(as modifier): twin carburettors

3.
Also called macle. a crystal consisting of two parts each of which has a definite orientation to the other
verb twins, twinning, twinned
4.
to pair or be paired together; couple
5.
(intransitive) to bear twins
6.
(intransitive) (of a crystal) to form into a twin
7.
(intransitive) (archaic) to be born as a twin
8.
(transitive)

to create a reciprocal relation between (two towns in different countries); pair (a town) with another in a different country
(intransitive) (of a town) to be paired with a town in a different country

twin (twĭn)
n.
One of two offspring born at the same birth. adj.

Being two or one of two offspring born at the same birth.

Consisting of two identical or similar parts; double.

twin
(twĭn)

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.

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.