fealty
noun /ˈfiːəlti/
/ˈfiːəlti/
[uncountable] (old use)- a promise to be loyal to somebody and show them your support, especially a king or queen
（尤指对君主的）效忠宣誓 词源Middle English: from Old French feau(l)te, fealte, from Latin fidelitas, from fidelis ‘faithful’, from fides ‘faith’.