chatelaine (n.)

1845, "mistress of a castle or household," from French châtelaine "a female castellan; wife of a castellan; mistress of a castle or country house;" fem. of châtelain, from Old French chastelain "owner and lord of a castle, nobleman; keeper of a castle" (Modern French châtelaine), from chastel "castle," from Latin castellum "castle" (see castle (n.)). In fashion, as a type of ornamental belt, from 1851; it is supposed to resemble a chain of keys such as a chatelaine would wear.