Lewis & Short

discessĭo, ōnis, f. [discedo].

  1. I. (Very rarely), a separation of married persons, Ter. And. 3, 3, 36; of the people into parties (with seditio), Gell. 2, 12: stellarum et discessiones et coetus, separations and conjunctions, id. 14, 1, 8; cf.: plebei a patribus, et aliae dissensiones, Sall. H. Fragm. 1, 9 Dietsch.
  2. II. A going away, departure, removal.
    1. A. In gen. (very rarely; cf. discessus): Nonanus desolatus aliorum discessione, Tac. A. 1, 30 fin.: necessaria, Macr. S. 1, 5, 3.
      Far more freq.,
    2. B. In partic.
      1. 1. Polit. t. t., a going over to any one in voting: senatusconsultum de supplicatione per discessionem fecit, Cic. Phil. 3, 9 fin.; Tac. A. 6, 12; Suet. Tib. 31; cf. Varr. ap. Gell. 14, 7, 12.
        Esp.: discessionem facere, to make a division, i. e. to get the vote of the house by dividing it, Cic. Phil. 14, 7 fin.; Hirt. B. G. 8, 52 fin.; 8, 53; Cic. Sest. 34, 74; Tac. A. 3, 69 fin. al.
      2. 2. In the church, a separation, schism (eccl. Lat.), Vulg. Act. 21, 21; id. 2 Thes. 2, 3.