Lewis & Short

trīcēnārĭus, a, um, adj. [triceni], of or containing thirty: fistula, thirty quarterdigits in diameter, Front. Aquaed. 29; 48: filius, thirty years old, Sen. Excerpt. Controv. 3, 3 fin.: homo, Arn. 2, 58; Pall. Aug. 12; Front. Aquaed. 29; 48.