The Collaborative International Dictionary of English v.0.48:

Copulation \Cop`u*la"tion\, n. [L. copulatio: cf. F.
   copulation.]
   1. The act of coupling or joining; union; conjunction.
      [1913 Webster]

            Wit, you know, is the unexpected copulation of
            ideas.                                --Johnson.
      [1913 Webster]

   2. The coming together of male and female in the act of
      generation; sexual union; coition.
      [1913 Webster]

WordNet (r) 3.0 (2006):

copulation
    n 1: the act of sexual procreation between a man and a woman;
         the man's penis is inserted into the woman's vagina and
         excited until orgasm and ejaculation occur [syn: sexual
         intercourse, intercourse, sex act, copulation,
         coitus, coition, sexual congress, congress, sexual
         relation, relation, carnal knowledge]