FIDELITY, ALLEGIANCE, FEALTY, LOYALTY, DEVOTION, PIETY mean faithfulness to something to which one is bound by pledge or duty.

FIDELITY implies strict and continuing faithfulness to an obligation, trust, or duty.

e.g. marital fidelity

ALLEGIANCE suggests an adherence like that of citizens to their country.

e.g. pledging allegiance

FEALTY implies a fidelity acknowledged by the individual and as compelling as a sworn vow.

e.g. fealty to the truth

LOYALTY implies a faithfulness that is steadfast in the face of any temptation to renounce, desert, or betray.

e.g. valued the loyalty of his friends

DEVOTION stresses zeal and service amounting to self-dedication.

e.g. a painter's devotion to her art

PIETY stresses fidelity to obligations regarded as natural and fundamental.

e.g. filial piety

faithfulness to a person, cause, or belief, demonstrated by continuing loyalty and support:

｟かたく｠ 【人･組織･主義などに対する】忠実, 忠誠; 誠実 «to»

e.g. he sought only the strictest fidelity to justice.

sexual faithfulness to a spouse or partner.

【夫･妻に対する】貞節 «to»

the degree of exactness with which something is copied or reproduced:

｟かたく｠ 【真理･事実などに】合致すること, 真に迫ること «to» ; (複製などの)正確さ

e.g. the 1949 recording provides reasonable fidelity.

late Middle English: from Old French fidelite or Latin fidelitas, from fidelis ‘faithful’, from fides ‘faith’. Compare with fealty.