Infidelity

Part of speech: noun (n.)

1. Want of faith or belief in some religious system; especially, a want of faith in, or disbelief of, the inspiration of the Scriptures, of the divine origin of Christianity. There is, indeed, no doubt but that vanity is one of the principal causes of infidelity. V. Knox.

2. Unfaithfulness to the marriage vow or contract; violation of the marriage covenant by adultery.

3. Breach of trust; unfaithfulness to a charge, or to moral obligation; treachery; deceit; as, the infidelity of a servant. "The infidelity of friends." Sir W. Temple.