Lewis & Short

cŏĭtĭo, ōnis, f. [coëo].

  1. * I. A coming or meeting together, a meeting: prima coitio est acerrima, Ter. Phorm. 2, 2, 32.
  2. II. Esp.
    1. A. A uniting, banding together.
      1. 1. In gen. (rare): societatis, Dig. 17, 2, 70.
      2. 2. In partic., in a bad sense, a conspiracy, plot, coalition (several times in Cic. and Liv.; elsewh. rare): suspitio coitionis, Cic. Planc. 22, 53; id. Clu. 54, 148: non factionibus modo nec per coitiones usitatas nobilibus, etc., Liv. 7, 32, 12; cf. id. 2, 35, 4; 3, 35, 9: candidatorum consularium, Cic. Q. Fr. 3, 1, 5, § 16: Memmii, id. ib. 2, 14 (15), 4: tribunorum, Liv. 3, 65, 8: facere, Cic. Planc. 22, 53; Liv. 9, 26, 9: dirimere, Cic. Att. 4, 18, 3.
    2. B. Sexual intercourse, coition (post-class. for coitus), Macr. S. 7, 16; Cod. Th. 15, 8, 2; Sol. 49 fin.; Lact. 1, 8, 6.