formidable.

Powerful, capable, or difficult enough to make someone cautious or impressed.

Use it for

Words that belong together

• formidable challenge
• formidable opponent

On the page

The archive presented a formidable challenge to a single researcher.

Usage notes

Primary category: academic / formal. Forms: Comparative more formidable; superlative most formidable 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: analysis, evaluation, qualification. Commonness: moderately common.