n. [ LL. trentale, fr. L. triginta thirty; akin to tres three: cf. OF. trentel. See Three, and cf. Trigintal. ] 1. (R. C. Ch.) An office and mass for the dead on the thirtieth day after death or burial. “Their trentals and their shrifts.” Spenser. [ 1913 Webster ]
(Geol.) A subdivision in the lower Silurian system of America; -- so named from Trenton Falls, in New York. The rocks are mostly limestones, and the period is divided into the Trenton, Utica, and Cincinnati epochs. See the Chart of Geology. [ 1913 Webster ]