vīcennālis, e, adj. vicennium, of twenty years, every twenty years (postclass.). Adj.: votis vicennalibus, Num. Alex. Sev. ap. Eckhel. D. N. V. 7, p. 275.
— Subst.: vīcennālia, ium, n., a festival on the twentieth anniversary of an emperor's reign, Lact. Mort. Pers. 17.