"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- "not" (see in- (1)), + cincta, fem. of cinctus, past participle of cingere "to gird" (see cinch). But the Late Latin word is more likely from Latin inciens "pregnant," from in- (2) "in, into" + second element from PIE root *keue- "to swell," also "vault, hole." Modern form is from 18c., perhaps a reborrowing from French.