Lewis & Short

dēcīsĭo, ōnis, f. [2. decīdo].

  1. I. (Acc. to decīdo, no. II. B.) A diminishing: luminis, App. de Mundo, p. 71, 4.
    Far more freq., and in good prose.
  2. II. (Acc. to decīdo, no. II. A.) A decision, settlement, agreement: nostra de aequitate, Cic. Caecin. 36 fin.: dicat decisionem factam esse, quae facta non est, id. Rosc. Com. 13, 48; id. Flacc. 36, 89; id. Verr. 2, 1, 54: quaestionis, Dig. 5, 3, 25.