in-fidēlis, e, adj., that cannot be relied upon, unfaithful, faithless. In gen. (rare but class.): si hoc sibi sument, nullam esse fidem, quae infideli data sit, Cic. Off. 3, 29, 106: Bellovaci, qui ante erant per se infideles, Caes. B. G. 7, 59: non infideles arbitrae Nox et Diana, Hor. Epod. 5, 50: obsecro, infidelior mihi ne fuas, quam ego sum tibi, Plaut. Capt. 2, 3, 83: ut ex infidelissimis (sociis) firmissimos redderem, Cic. Fam. 15, 4, 14: silex ad structuram infidelis, Plin. 36, 22, 49, § 169: infidelis recti magister est metus, Plin. Pan. 45.

— In partic., in eccl. Lat., unbelieving, infidel: Christiani, Salv. de Gub. 5 init.

—Adv.: in-fidēliter, faithlessly, perfidiously: nec me minus putarem reprehendendum, si inutiliter aliquid senatui suaserim quam si infideliter, Cic. Brut. 2, 1, 2; Vulg. Isa. 21, 2.

—Sup.: infidelissime, Salv. contra Avar. 3.