Someone guilty of infidelity is cheating on a spouse or romantic partner. A common cause of divorce and heartbreak is infidelity.

Fidel means "faithful" or "loyal." Tack on the prefix in, which means "not," and you've got yourself infidelity — the act of being unfaithful. The word can also be used to refer to someone's religious beliefs. Run angrily through a church and claim that God doesn't exist, and your fellow churchgoers will think you lack faith, or that you are guilty of infidelity.

Definitions of infidelity

n the quality of being unfaithful

faithfulness, fidelity
the quality of being faithful
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faithlessness, falseness, fickleness, inconstancy
unfaithfulness by virtue of being unreliable or treacherous
the quality of being disloyal
disloyalty to the government or to established authority
subversiveness, traitorousness, treason
disloyalty by virtue of subversive behavior
perfidiousness, perfidy, treachery
betrayal of a trust
Type of:
an essential and distinguishing attribute of something or someone

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