O.E. hem "a border," from P.Gmc. *khamjanan (cf. O.N. hemja "to bridle, curb," O.Fris. hemma "to hinder," M.Du., Ger. hemmen "to hem in, stop, hinder"), from the same root that yielded hamper and O.E. hamm, common in place names (where it means "enclosure, land hemmed in by water or high ground, land in a river bend"). The phrase hem in "shut in, confine," first recorded 1538. Hem-line first attested 1923.