merciless.

Showing no pity or relief when causing difficulty or suffering.

Use it for

Words that belong together

• merciless criticism
• merciless heat

On the page

Merciless heat drove everyone into the narrow strip of shade.

Usage notes

Primary category: literary / elevated general. Forms: Comparative more merciless; superlative most merciless 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.