faithless.

1. Failing to remain loyal or keep a promise or trust.

2. Not holding religious faith or confidence in a spiritual belief.

Use it for

Words that belong together

• faithless ally
• faithless promise

On the page

She would not plead with a faithless ally.

Usage notes

Primary category: literary / elevated general. Forms: Comparative more faithless; superlative most faithless when comparison is meaningful. Legacy lexical fields mirror sense 1 only. Use numbered sense fields for all meanings. Established modern English lexical item. No separate regional spelling or grammatical inflection entry. Commonness: moderately common.