Lewis & Short

1. congressus, a, um, Part., from congredior.

2. congressus, ūs, m. [congredior], a coming or going together, in a friendly or hostile manner (class. in prose and poetry).

  1. I. A friendly meeting, a social assembly, conference, conversation, etc.: omnes congressum tuum fugiunt, Cic. Sest. 52, 111; id. Phil. 12, 11, 26; id. Att. 1, 17, 2: si quis congressus fuerit mihi cum Caesare, id. ib. 11, 12, 3; id. Cael. 8, 20; Liv. 7, 4, 4; Quint. 1, 2, 20; Tac. A. 13, 46 et saep.
    In plur., Cic. Or. 10, 33; id. Lael. 23, 87; Liv. 1, 19, 5; 7, 40, 3; Tac. A. 2, 28; Verg. A. 5, 733 al.
    Also of the companionship of animals, Cic. N. D. 2, 48, 124; Quint. 1, 2, 20.
    1. B. Pregn., a close union, combination (very rare): materiaï, Lucr. 5, 68; cf.: duriorum (consonantium) inter se, Quint. 11, 3, 35.
      In plur., Lucr. 2, 1065.
      Hence, carnal union, copulation: feminarum, Plin. 12, 14, 30, § 54; cf. congressio, I. B.
  2. II. A hostile encounter, a contest, fight, Cic. de Or. 2, 78, 317: cum his navibus nostrae classi ejusmodi congressus erat, ut, etc., Caes. B. G. 3, 13; id. B. C. 1, 46: magnam cladem in congressu facere, Sall. J. 59, 3; 74, 3; Tac. A. 2, 3; Verg. A. 12, 514; Val. Fl. 6, 322 al.
    Also of judicial contests, Quint. 3, 6, 4.