Source : Webster's Revised Unabridged Dictionary (1913)

Copulate \Cop"u*late\, a. [L. copulatus, p. p. of copulare to
   couple, fr. copula. See {Copula}.]
   1. Joined; associated; coupled. [Obs.] --Bacon.

   2. (Gram.) Joining subject and predicate; copulative. --F. A.
      March.

Copulate \Cop"u*late\, v. i. [imp. & p. p. {Copulated}; p. pr. &
   vb. n. {Copulating}.]
   To unite in sexual intercourse; to come together in the act
   of generation.

Source : WordNet®

copulate
     v : make love; "Birds mate in the Spring" [syn: {mate}, {pair},
         {couple}]