這些單詞均有效忠的含義。相比之下，allegiance多指義務上的忠誠，如公民效忠其國家或王國[1]，如oath of allegiance； 同時其也用于表示政治或原則等方面的忠誠。fealty則專門用于封建王朝封臣或奴隸等對封建主的效忠[2]。fidelity常表示一種強烈的奉獻精神，有依附和固執(zhí)的含義[3]，如：His fidelity to the principles of justice never wavered. 比較之下，loyalty 則更多帶有個人關系色彩，表示強烈的個人承諾，具有熱愛和獻身的含義，常用于對個人、事業(yè)、責任或政府的忠誠[4]。
[1 ] “ Obedience owed to the sovereign or government. ” Cf. Daphne Dukelow, The Dictionary of Canadian Law，at p. 37, A Carswell Publication (1991).
[2] " In feudal law, fidelity；allegiance to feudal lord of the manor； the feudal obligation resting upon the tenant or vassal by which he was bound to be faithful and true to his lord, and render him obedience and service. ” Cf. The Publisher's Editorial Staff, Black's law Dictionary, abridged 6th edition, at p. 422, West Publishing Co. (1991).
[3] "Fidelity implies a strong and faithful dedication. " Cf. The Editors of the Reader's Digest, Use the Right Word, at p. 11, The Reader's Digest Association Proprietary Ltd. (1971).
[4] "Faithfulness or allegiance to a person, cause, duty, or government. ”Cf. Bryan A. Gamer, Black's Law Dictionary, 7th edition, at p. 959，West Group (1999).