tricennium

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.

trīcennĭum, ii, n. [triginta-annos],

the space of thirty years , Cod. Just. 7, 31, 1; Sid. Ep. 8, 6 med. ; Cassiod. Var. 1, 18; 3, 31.