Lewis & Short

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

nĕfastus, a, um, adj. [nefas].

  1. I. Lit. (opp. to fastus): dies nefasti, days on which judgment could not be pronounced or assemblies of the people be held: fastis diebus jura fari licebat, nefastis quaedam non licebat fari, Paul. ex Fest. p. 93 Müll.: nefasti dies notantur N littera, quod iis nefas est praetori, apud quem lege agitur, fari tria verba: do, dico, addico, Paul. ex Fest. p. 165 Müll.; v. 1. fastus: ille (Numa) nefastos dies fastosque fecit, quia aliquando nihil cum populo agi, utile futurum erat, Liv. 1, 19, 7; Varr. L. L. 6, 4, 30; Ov. F. 1, 47; Gai. Inst. 4, 29.
  2. II. Transf.
    1. A. For nefas, contrary to the sacred rites or to religion; irreligious, impious: QVAE AVGVR INIVSTA, NEFASTA, DEFIXERIT, Fragm. XII. Tab. ap. Cic. Leg. 2, 8 fin.: prolibare dis nefastum habetur, etc., Plin. 14, 19, 23, § 119.
      1. 2. In gen., wicked, profane, abandoned: homines ad hanc rem idonei; nam istorum nullus nefastust, Plaut. Poen. 3, 2, 7.
        Esp., subst.: nĕfastum, i, n. (sc. crimen), a wicked deed, abomination, profanity (poet. and in post-Aug. prose): quid intactum nefasti Liquimus? profane, criminal, Hor. C. 1, 35, 35; Plin. 4, 11, 18, § 47.
    2. B. Unlucky, inauspicious = funestus, ater (not anteAug.): ille et nefasto te posuit die, etc., Hor. C. 2, 13, 1: cum diem natalem ejus (Agrippinae) inter nefastos referendum suasisset, Suet. Tib. 53; Tac. A. 14, 12 init.: ne qua terra sit nefasta victoriae suae, Liv. 6, 28, 8: Acheron, Stat. Th. 4, 456: loca, id. ib. 1, 273: religiosi dies dicuntur tristi omine infames … quos multitudo imperitorum prave et perperam nefastos appellat, Gell. 4, 9, 5.
    3. C. Hurtful, injurious: innocentiorem tamen esse marem (fruticem); eaque causa est ne inter nefastos frutex damnetur, Plin. 20, 11, 44, § 114.