Lewis Short
(adj.adv.) : fătŭus, a, um, adj.root fa, cf. for; properly, garrulous
* Foolish, silly, simple (class.; syn.: stultus, stolidus, insipiens, desipiens, stupidus, hebes, ineptus, insulsus, absurdus).
* Adj.: ego me ipsum stultum existimo, fatuum esse non opinor, Afran. ap. Isid. Orig. 10, 246: stulti, stolidi. fatui, fungi, bardi, blenni, buccones,Plaut. Bacch. 5, 1, 2: fatuus est, insulsus,Ter. Eun. 5, 9, 49: non modo nequam et improbus, sed etiam fatuus et amens es,Cic. Deiot. 7, 21: monitor,id. de Or. 2, 24, 99: homo, Poët. ap. Cic. de Or. 2, 67, 274: puer,Cic. Att. 6, 6, 3: nisi plane fatui sint,id. Fin. 2, 22, 70: mores,Plaut. Trin. 2, 2, 18.
* Poet. transf.
* Subst.: fătŭus, i, m., and fătŭa, ae, f., a fool, simpleton, a jester, buffoon.
* Awkward, clumsy, unwieldy: illa bipennem Insulsam et fatuam dextra tenebat,Juv. 6, 658.
* In gen., one who acts foolishly: paene ecfregisti, fatue, foribus cardines,Plaut. Am. 4, 2, 6; Cat. 83, 2; Juv. 9, 8.
* Esp., kept by Romans of rank for their amusement: Harpasten, uxoris meae fatuam, scis hereditarium onus in domo mea remansisse ... si quando fatuo delectari volo, me rideo,Sen. Ep. 50, 2; Lampr. Comm. 4, 3.—Hence, fătŭe, adv., foolishly, absurdly: plerumque studio loquendi fatue modo accedendum,Quint. 6, 4, 8 dub. (Spald. and Zumpt, fatui); Tert. adv. Herm. 10; id. de Pat. 6. —Hence
Charlton T. Lewis, Charles Short, A Latin Dictionary