either of two offspring born to the same mother at the same birth
either of two people or things closely related to or resembling each other
either of two offspring born to the same mother at the same birth: see fraternal (2), identical (3)
(used before a noun) relating to or denoting a person or animal that is a twin
a twin sister
either of two people or things corresponding to or resembling each other
(used before a noun) relating to or denoting two people or things of this kind
twin engines
a compound crystal composed of two or more parts of the same kind that have a definite orientation to each other