Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
dĭūtĭne, adv., v. the foll. fin.
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.