Concilium (from con-calare) is an assembly (Fest. p. 38) that has been called; also used in a transferred sense (Cic. Tusc. 1,72; Lucr. 3,805).
1. In political usage, concilium frequently differentiates a popular assembly without legal consequences from constitutional contiones and comitia (is qui non universum populum, sed partem aliquam adesse iubet, non comitia, sed concilium edicere iubet, Gell. NA 15,27,4; Liv. 9,45,8). It was also used in the meaning of contio or comitia and then more often in association with populi and plebis (Cic. Sest. 65; lex Iulia muni…