·noun Unfaithfulness to the marriage vow or contract; violation of the marriage covenant by adultery.
II. Infidelity ·noun Breach of trust; unfaithfulness to a charge, or to moral obligation; treachery; deceit; as, the infidelity of a servant.
III. Infidelity ·noun 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.