1. noun /twɪn/
a) Either of two people (or, less commonly, animals) who shared the same uterus at the same time; one who was born at the same birth as a sibling.
b) Either of two similar or closely related objects, entities etc.
2. adjective /twɪn/
a) Forming a pair of twins.
the twin boys
b) Forming a matched pair.
twin socks
3. verb /twɪn/
Placetown in England is twinned with Machinville in France.
b) To give birth to twins.
For example, Coventry twinned with Dresden as an act of peace and reconciliation, both cities having been heavily bombed during the war.
Wikipedia foundation.