Lewis & Short

dĭūtĭnus, a, um, adj. [diu], of long duration, lasting, long (rare but class.; cf.: longinquus, diuturnus): (supplicium) longum diutinumque a mane ad vesperum, Plaut. Mil. 2, 6, 28: mansiones Lemni, *Ter. Ph. 5, 8, 23: servitus, Cic. Fam. 11, 8, 2: laetatio (opp. longior dolor), Caes. B. G. 5, 52 fin.: labor, id. B. C. 2, 13, 2; 2, 14, 1: conclusio, id. ib. 2, 22, 1: militia, Liv. 5, 11: bellum, id. 25, 1: pax, id. 6, 33: otium, id. 25, 7: morbus, Suet. Calig. 1 et saep.
Comp. and sup. do not occur.
Adv.: diū-tĭne, long, a long time: uti, Plaut. Rud. 4, 7, 15: sermocinans, App. M. 2, p. 121, 15.