late 15c., "characteristic of a man; marked by manly force," from Middle French viril (14c.) and directly from Latin virilis "of a man, manly, worthy of a man," from vir "a man, a hero," from PIE *wi-ro- "man, freeman" (cognates: Sanskrit virah, Avestan vira-, Lithuanian vyras, Old Irish fer, Welsh gwr, Gothic wair, Old English wer "man"). Virile member for "penis" is recorded from 1540s.