Lewis & Short

mentĭor, ītus, 4 (fut. mentibitur, for mentietur, Plaut. Mil. 1, 1, 35; 2, 2, 99; v. Neue, Formenl. 2, p. 448), v. dep. n. and a. [prob. from root men-, whence mens, memini, q. v. Original meaning, to invent; hence],

  1. I. Neutr., to lie, cheat, deceive, etc.: mentiri palam, Plaut. Truc. 1, 2, 89: mentire, id. Poen. 3, 5, 18: adversus aliquem, id. Aul. 4, 7, 9: apud aliquem, id. Poen. 1, 1, 24: sibi, id. Am. 1, 2, 6: mihi, id. Capt. 3, 5, 46; Ter. Eun. 4, 4, 35: aperte, Cic. Ac. 2, 6, 18: in re aliquā, id. Att. 12, 21, 4: de re aliquā, id. N. D. 3, 6, 14: adeo veritatis diligens, ut ne joco quidem mentiretur, Nep. Epam. 3, 1.
    With acc. and inf., to pretend, to declare falsely: certam me sum mentitus habere Horam, quae, etc., Ov. Tr. 1, 3, 53; Plin. 12, 15, 34, § 67: mentior nisi or si mentior, a form of asseveration, I am a liar, if, etc.: mentior, nisi et quae alunt illud, corpora sunt, Sen. Ep. 106, 5: si mentiar, inquit, Ultima, quā fallam, sit Venus illa mihi, Ov. F. 4, 227.
    Of things, to deceive, impose upon: frons, oculi, vultus persaepe mentiuntur, oratio vero saepissime, Cic. Q. Fr. 1, 1, 6: in quibus nihil umquam … vetustas mentita sit, id. N. D. 2, 5, 15.
    1. B. To deceive one’s self, mistake: mentire, gnate, Plaut. Trin. 2, 2, 83 Brix ad loc.
  2. II. Act., to lie or speak falsely about, to assert falsely, make a false promise about; to feign, counterfeit, imitate a shape, nature, etc.: cujus consilio tantam rem mentitus esset, had devised such a falsehood, Sall. C. 48: originem alicujus, Just. 35, 2, 4: auspicium, Liv. 10, 40: titulum Lyciscae, to assume falsely, Juv. 6, 123: noctem, to promise falsely, Prop. 3, 9, 1: cur sese daemonia mentiuntur, Tert. Apol. 23; also, to invent, feign, of a poetical fiction: ita mentitur (sc. Homerus), Hor. A. P. 151; cf.: poëtae Orionem mentiuntur in pelago incidentem, Lact. 4, 15, 21.
    Pass.: si a debitore, praelato die, pignoris obligatio mentiatur, Dig. 48, 10, 28.
    1. B. Trop., of inanim. subjects: semel fac illud, Mentitur tua quod subinde tussis, do what your cough keeps falsely promising, i. e. die, Mart. 5, 39, 6: mentiris juvenem tinctis capillis, id. 3, 43, 1: color, qui chrysocollam mentitur, Plin. 35, 6, 29, § 48: nec varios discet mentiri lana colores, Verg. E. 4, 42: sexum viris denegatum muliebri motu, Col. praef. 1.
      Hence,
      1. * 1. mentĭens, entis, m. subst., a fallacy, sophism: quomodo mentientem, quem ψευδόμενον vocant, dissolvas, Cic. Div. 2, 4, 11.
      2. 2. mentītus, a, um, Part., in pass. signif., imitated, counterfeit, feigned (poet.): mentita tela, Verg. A. 2, 422: figurae, Ov. M. 5, 326: fama, id. ib. 10, 28: nomen, id. ib. 10, 439; id. H. 11, 73; Sen. Contr. 5, 5, 3; Luc. 2, 512; Val. Fl. 6, 698; 7, 155; Sil. 15, 796; Stat. S. 4, 6, 21; id. Th. 1, 256; 7, 303; 10, 875; Poët. ap. Suet. Oth. 3; Prop. 4 (5), 7, 58: mentiti fictique terrores, Plin. Ep. 6, 20, 15; id. Pan. 81, 3: divinitas, Lact. 2, 16, 2; Quint. 12, 10, 76.