# infidelity

/ˌɪnfɪˈdɛɫɪti/ (US) · /ˌɪnfɪdˈɛlɪti/ (UK)

Source: https://englishreference.com/word/infidelity
Updated: 2026-08-27

## Senses

### 2. breach of duty

noun · CEFR C2 · Formal

a failure to be loyal to a promise, a duty, or a set of beliefs.

For teachers: a breach of trust or a failure to remain loyal to a moral or professional obligation.

- The general was accused of infidelity to the crown.
- The philosopher argued that intellectual infidelity — the betrayal of one's own logic for personal gain — was the greatest vice of the age.

### 3. lack of religious faith

noun · CEFR C2 · Archaic · Formal

a lack of belief in a particular religion or in God.

For teachers: the state of having no religious belief or of rejecting a specific faith.

- In the past, people were sometimes punished for their religious infidelity.
- The medieval text contains a lengthy polemic against the perceived infidelity of neighboring tribes who refused to convert.

Teaching tip: This sense is rarely used in modern conversation; 'atheism' or 'secularism' is preferred unless discussing historical religious conflicts.

## Examples

- The couple went to therapy after his infidelity was discovered.
- Many marriages struggle to survive the breach of trust caused by a single instance of infidelity.
- The novel explores the emotional fallout of infidelity, focusing less on the act itself and more on the slow erosion of intimacy that precedes the betrayal.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.