late 14c., progenitour, "an ancestor in the direct line," from Anglo-French progenitour (mid-14c.), Old French progeniteur (14c.) and directly from Latin progenitor "ancestor, the founder of a family," agent noun from progenitus, past participle of progignere "beget," from pro "forth" (see pro-) + gignere "to produce, beget" (from PIE root *gene- "give birth, beget"). Related: Progenitive; progenital; progenitorial. Fem. form progenitrix is from c. 1600; progenitress from 1610s.