perfĭdĭōsus, a, um, adj. [perfidia], faithless, dishonest, treacherous, false, perfidious (class.).
I Of persons: fallax, perfidiosus, Cic. Pis. 27, 66: perfidiosus et subdolus animo, Tac. A. 16, 32.— Sup. : omnium perfidiosissimus, Cic. N. D. 3, 32, 80.—
II Of inanim. and abstr. things: amor, Plaut. Cist. 1, 1, 73: nihil perfidiosum et insidiosum et fallax in amicitiā, Cic. Fam. 3, 10, 7; id. Rosc. Com. 6, 16.—Adv.: per-fĭdĭōsē , faithlessly , dishonestly , treacherously , perfidiously (rare but class.): hercle istam rem judicasti perfidiose, Plaut. Curc. 5, 3, 41: multa perfidiose facta, Cic. Rosc. Am. 40, 118: perfidiose, crudeliter factum, Auct. Her. 1, 5, 8.— Comp. : perfidiosius rebellantes, Suet. Aug. 21.