Fealty descends from Old French féauté, a worn-down form of Latin fidēlitātem (faithfulness), from fidēs (faith, trust), PIE *bʰeydʰ- (to trust). A doublet of fidelity — both from the same Latin word but via different routes. In feudal law it was the oath of loyalty a vassal swore to a lord, distinct from the more intimate bond of homage.
A feudal tenant's or vassal's sworn loyalty and obligation of fidelity to a lord; more broadly, faithful allegiance or devotion to a person, cause, or duty.
From Old French feauté and féauté (fidelity, loyalty, faithfulness), from Latin fidēlitātem (accusative of fidēlitās, faithfulness, loyalty), from fidēlis (faithful, trustworthy), itself from fidēs (faith, trust, belief), from PIE *bʰeydʰ- (to trust, to confide, to persuade). The PIE root *bʰeydʰ- also underlies Latin foedus (treaty, covenant), fīdus (trusty), and through Germanic *bīdaną produced English bide and abide. The word entered Middle English around 1300 as feaute or feute, directly from the Anglo-French legal
Fealty and fidelity are linguistic doublets — twin descendants of the same Latin word fidēlitātem that arrived in English by different routes. Fealty took the popular path through Old French, where centuries of sound changes wore fidēlitātem down to féauté. Fidelity walked the scholarly corridor, borrowed directly