indefatigable.

Showing tireless persistence in effort.

Use it for

Words that belong together

• indefatigable worker
• indefatigable energy

On the page

The indefatigable clerk pursued every missing record.

Usage notes

Primary category: literary / elevated general. Forms: Comparative more indefatigable; superlative most indefatigable 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. Writing functions: character, description. Commonness: moderately common.