The Collaborative International Dictionary of English v.0.48:

Intercourse \In"ter*course\, n. [Formerly entercourse, OF.
   entrecours commerce, exchange, F. entrecours a reciprocal
   right on neighboring lands, L. intercursus a running between,
   fr. intercurrere to run between. See Inter-, and Course.]
   1. A commingling; intimate connection or dealings between
      persons or nations, as in common affairs and civilities,
      in correspondence or trade; communication; commerce;
      especially, interchange of thought and feeling;
      association; communion.
      [1913 Webster]

            This sweet intercourse
            Of looks and smiles.                  --Milton.
      [1913 Webster]

   2. Same as sexual intercourse.
      [PJC]

   Sexual intercourse, sexual or carnal connection; coition;
      copulation, especially between humans.

   Syn: Communication; connection; commerce; communion;
        fellowship; familiarity; acquaintance.
        [1913 Webster]

WordNet (r) 3.0 (2006):

intercourse
    n 1: communication between individuals [syn: intercourse,
         social intercourse]
    2: 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]

Moby Thesaurus II by Grady Ward, 1.0:

195 Moby Thesaurus words for "intercourse":
   ESP, accord, act of love, addition, adjunct, adultery, affairs,
   affiliation, affinity, agglomeration, agglutination, aggregation,
   alliance, alternation, answer, aphrodisia, approximation,
   articulation, ass, assemblage, association, balance of trade,
   balling, big business, bond, bracketing, business,
   business dealings, carnal knowledge, climax, closeness, clustering,
   coaction, cohabitation, coition, coitus, coitus interruptus,
   collegiality, colloquial discourse, colloquy, combination,
   commerce, commercial affairs, commercial relations, communication,
   communion, community, complementary distribution, concatenation,
   concourse, concurrence, confluence, congeries, conglomeration,
   congress, conjugation, conjunction, connectedness, connection,
   contact, contiguity, contrariety, convergence, conversation,
   converse, conversing, cooperation, copula, copulation,
   correspondence, coupling, dealing, dealings, deduction, diddling,
   discourse, disjunction, engagement, exchange, fair trade,
   fellowship, filiation, fornication, free trade, gathering,
   give-and-take, homology, hookup, industry, information,
   interaction, interchange, intercommunication, intercommunion,
   interlacing, interlinking, interlocution, intermeshing, interplay,
   intertwining, interweaving, interworking, intimacy, joinder,
   joining, jointure, junction, knotting, liaison,
   linguistic intercourse, link, linkage, linking, lovemaking,
   making it with, marital relations, market, marketing, marriage,
   marriage act, mating, meat, meeting, mercantile business,
   merchantry, merger, merging, mesh, meshing, message,
   multilateral trade, mutual attraction, nearness, onanism, orgasm,
   ovum, pairing, pareunia, procreation, propinquity, proximity,
   quid pro quo, rapping, rapport, reciprocal trade, relatedness,
   relation, relations, relationship, reply, response,
   restraint of trade, screwing, seesaw, sex, sex act, sexual climax,
   sexual commerce, sexual congress, sexual intercourse,
   sexual relations, sexual union, similarity, sleeping with,
   small business, social activity, social intercourse,
   social relations, speaking, speech, speech circuit,
   speech situation, sperm, splice, symbiosis, sympathy, talking,
   telepathy, the business world, the marketplace, tie, tie-in,
   tie-up, tit for tat, touch, trade, traffic, truck,
   two-way communication, unification, unilateral trade, union,
   venery, verbal intercourse, yoking



Bouvier's Law Dictionary, Revised 6th Ed (1856):

INTERCOURSE. Communication; commerce; connexion by reciprocal dealings
between persons or nations, as by interchange of commodities, treaties,
contracts, or letters.