"apparel for covering the front of a person" (especially while at work, to keep clothes clean), mid-15c., faulty separation (as also in adder, auger, umpire) of a napron (c. 1300), from Old French naperon "small table-cloth," diminutive of nappe "cloth," from Latin mappa "napkin." Napron was still in use as recently as late 16c. The shift of Latin -m- to -n- was a tendency in Old French (conter from computare, printemps from primum, natte "mat, matting," from matta).
Extended 17c. to things which resemble or function like an apron. Symbolic of "wife's business" from 1610s; apron-string tenure was in reference to property held in virtue of one's wife, or during her lifetime only.
Even at his age, he ought not to be always tied to his mother's apron string. [Anne Brontë, "The Tenant of Wildfell Hall," 1848]