fallenEnglishOxford American Thesaurusfallen adjective 1 he attended a mass for his fallen comrades: dead, killed, murdered, slain, slaughtered, perished, expired, deceased; lost, late, lamented, departed, gone; rare demised. ▷antonyms surviving. 2 dated they encouraged the moral reform of fallen women: immoral, loose, promiscuous, unchaste, sinful, depraved, degenerate, impure, sullied, tainted, dishonored, disgraced, ruined, shamed. ▷antonyms chaste; pure.