Merriam-Webster Collegiate Dictionary - fidelity

 noun  (plural -ties)  Etymology: Middle English fidelite, from Middle French & Latin; Middle French fidelite, from Latin fidelitat-, fidelitas, from fidelis faithful, from fides faith, from fidere to trust — more at bide  Date: 15th century  1.  a. the quality or state of being faithful  b. accuracy in details ; exactness  2. the degree to which an electronic device (as a record player, radio, or television) accurately reproduces its effect (as sound or picture) Synonyms:  ~, allegiance, fealty, loyalty, devotion, piety mean faithfulness to something to which one is bound by pledge or duty. ~ implies strict and continuing faithfulness to an obligation, trust, or duty marital ~. allegiance suggests an adherence like that of citizens to their country pledging allegiance. fealty implies a ~ acknowledged by the individual and as compelling as a sworn vow fealty to the truth. loyalty implies a faithfulness that is steadfast in the face of any temptation to renounce, desert, or betray valued the loyalty of his friends. devotion stresses zeal and service amounting to self-dedication a painter's devotion to her art. piety stresses ~ to obligations regarded as natural and fundamental filial piety.