fealty (n.)

c. 1300, feaute, from Old French feauté, earlier fealte, "loyalty, fidelity; homage sworn by a vassal to his overlord; faithfulness," from Latin fidelitatem (nominative fidelitas) "faithfulness, fidelity," from fidelis "loyal, faithful" (from PIE root *bheidh- "to trust, confide, persuade").