Lewis & Short

dēcrētōrĭus, a, um, adj. [decerno], belonging to a decision, decisive (post-Aug.): non accedit ad decretorium stilum, i. e. to a definitive sentence, Sen. Clem. 1, 14: intrepidus horam illam decretoriam (viz., the hour of death) prospice, id. Ep. 102 med.; so, dies, Plin. 18, 29, 69, § 288; cf. id. 18, 28, 68, § 272: arma, Sen. Ep. 117 med.; so Quint. 10, 5, 20: pugna, id. 6, 4, 6.