What does infidelity mean?
Infidelity is a noun meaning a failure to remain faithful, most commonly referring to sexual unfaithfulness between partners in a committed or marriage-like relationship. It can also describe a serious violation of loyalty, trust, or faithfulness to a promise, principle, or organization. The word often implies not merely an accidental failure but a deliberate betrayal, so it carries strong emotional and moral associations. In discussions of relationships, marital infidelity, and sexual infidelity, the term describes conduct that violates an explicit or understood commitment to exclusivity. Because it may also apply more broadly to political, professional, or institutional disloyalty, its sense depends on context: “infidelity to one's spouse” clearly concerns sexual unfaithfulness, while “infidelity to a cause” suggests betrayal of an allegiance. For a precise and forceful account of these distinctions, the word is especially useful when examining trust, betrayal, and the consequences of breaking promises.
nounInfidelity is a violation of the commitment to be sexually faithful to a partner. More broadly, it can refer to a serious breach of trust, loyalty, or fidelity to an agreement, principle, or institution.
- Sexual unfaithfulness by a person who has promised sexual fidelity to a partner.
- A serious breach of loyalty, trust, or faithfulness to a person, promise, principle, or institution.
"Her discovery of her partner's infidelity left her questioning the future of their relationship."
"The letter suggested that the manager's infidelity to the company had been deliberate."
"Her decision to leave was not merely about infidelity; it reflected a deeper loss of trust."
The plural is used for separate instances or acts of infidelity.
"The novel traces the infidelities and deceptions that divide the family."
Infidelity can mean not only a partner's betrayal of sexual trust, but also a betrayal of any deeply held trust.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does infidelity come from?
Infidelity entered English in the late Middle English period in the sense of unbelief or religious unfaithfulness. It ultimately derives from Latin infidelitas, formed from infidelis, “unfaithful,” which contains the root fidus, meaning faithful or trusted. The word's modern sense of sexual unfaithfulness developed as the older religious sense declined, while the related ideas of trust, loyalty, and fidelity continued to shape its meaning.
How infidelity is actually used
In modern usage, the word most often refers to sexual unfaithfulness, especially within a marriage or committed relationship. Its broader sense, a breach of loyalty or trust, is less common but established. The term can carry strong emotional and moral connotations.