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.

perfĭdē, adv., v. perfidus fin.

perfĭdus, a, um, adj. [per-fides], that breaks his promise, faithless, false, dishonest, treacherous, perfidious.

  1. I. Lit. (class.; syn. infidus): vanum et perfidiosum esse, Cic. Quint. 6, 26: omnes, aliud agentes, aliud simulantes, perfidi, improbi, malitiosi sunt, id. Off. 3, 14, 60.
          1. (β) With gen. (poet.): gens perfida pacti, faithless, Sil. 1, 5.
        1. b. Of inanim. and abstr. things (poet.): bella, Sil. 15, 819: nex, effected by treachery, Sen. Agam. 887: arma, Ov. F. 4, 380: verba, id. R. Am. 722.
        2. c. Adverb.: perfidum ridens Venus (= maligne ac dolose), Hor. C. 3, 27, 67.
          As subst.: perfĭdus, i, m., a scoundrel, Juv. 13, 245; 9, 82.
  2. II. Transf., treacherous, unsafe, dangerous (poet. and in post-class. prose): freta, Sen. Med. 302: saxa, id. Agam. 570: perfidum glacie flumen, Flor. 3, 4, 5: perfida et lubrica via, Prop. 4 (5), 4, 49: vappa, wretched wine that has a good appearance, Mart. 12, 48, 14.
    Sup.: homo, quoad vixerat, perfidissimus, Amm. 16, 12, 25.
    Adv.: perfĭ-dē, faithlessly, perfidiously, treacherously (post-Aug.): perfide recuperans, Sen. Contr. 4, 26: rumpere pactum, Gell. 20, 1, 54: agere, Dig. 26, 7, 55: quod perfide gestum est, ib. 44, 4, 4, § 13.