merciless

adjective

mer·​ci·​less ˈmər-si-ləs 

: having or showing no mercy : pitiless

the merciless killing of innocent people

mercilessly adverb

mercilessness noun

Synonyms of merciless

• ruthless
• stony

Examples of merciless in a Sentence

the merciless killing of innocent people

He has been merciless in his criticism of his opponent.

Recent Examples on the Web

The red card was rescinded; the team was unmoored; conspiracies grew overnight, like mushrooms; and a merciless Belgium swept in and trampled, 4–1, on what remained. — Anthony Lane, New Yorker, 17 July 2026

Soon enough, Karl’s seemingly foolproof blackmail scheme devolves into a merciless, dog-eat-dog fight for survival, and the two men are locked in a cutthroat collision course, their fates now inextricably linked. — Ryan Lattanzio, IndieWire, 15 July 2026

Tis hard to see the mighty prancing war horse, trampling the dying and dead beneath their merciless feet. — Rose Horowitch, The Atlantic, 8 July 2026

Humility is the posture; the standard is merciless. — Luis E. Romero, Forbes.com, 19 June 2026

Word History

First Known Use

14th century, in the meaning defined above

Rhymes for merciless

• transversalis

Kids Definition

merciless

adjective

mer·​ci·​less ˈmər-si-ləs 

: having no mercy : pitiless

merciless slaughter

mercilessly adverb

mercilessness noun