"pregnant, with child," c.1600, insente, from French enceinte "pregnant" (12c.), from Late Latin incincta (source of Italian incinta), explained by Isidore of Seville (7c.) as "ungirt," from Latin in-, privative prefix (see in-(1)), + cincta, fem. of cinctus, past participle of cingere "to gird" (see cinch). But perhaps the Late Latin word is from past participle of Latin incingere "to put into a girdle" (that is, "to make (a woman) pregnant"), with in- (2) "in, into." Modern form is 18c., perhaps a reborrowing from French.