Lewis & Short

congressĭo, ōnis, f. [congredior], a coming together, in a friendly or hostile manner.

  1. I. A friendly meeting, interview, conference (almost confined to Cic.), Cic. Clu. 14, 41; id. Phil. 2, 18, 46; id. Top. 15, 59; id. Fam. 7, 10, 4; opp. digressio, id. Q. Fr. 1, 3, 4.
    In plur.: in congressionibus familiarum, in familiar circles, Cic. Off. 1, 37, 132.
    1. B. A carnal union, copulation: maris et feminae, Cic. Rep. 1, 24, 38: uxoris, Lact. 6, 20, 25; cf. 2. congressus, I. B.
  2. II. A hostile meeting, an attack, contest (very freq. in Just., elsewhere rare, for the class. congressus), Claud. Quadrig. ap. Gell. 9, 13, 15; Just. 2, 12, 8; 4, 5, 1; 6, 4, 12; 12, 8, 4; 22, 3, 9; Lact. 3, 12, 4; 6, 6, 15 al.