Fidelity is the quality of being faithful or loyal. Dogs are famous for their fidelity.

Fidelity comes from the Latin root fides, which means faith, so fidelity is the state of being faithful. Marital fidelity is faithfulness to your spouse. If you're a journalist, your reports should have fidelity to the facts. Someone without fidelity to a religion or group belief is called an infidel.

Definitions of fidelity
  1. noun
    the quality of being faithful
    synonyms: faithfulness
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    infidelity, unfaithfulness
    the quality of being unfaithful
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    faithfulness and dependability in personal attachments (especially sexual fidelity)
    complete and wholehearted fidelity
    loyalty, trueness
    the quality of being loyal
    staunchness, steadfastness
    loyalty in the face of trouble and difficulty
    allegiance, fealty
    the loyalty that citizens owe to their country (or subjects to their sovereign)
    nationalism, patriotism
    love of country and willingness to sacrifice for it
    loyalty to the interests of a particular region
    type of:
    an essential and distinguishing attribute of something or someone
  2. noun
    accuracy with which an electronic system reproduces the sound or image of its input signal
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    type of:
    accuracy, truth
    the quality of being near to the true value
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