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

• ruthless

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

In the present day, Lockjaw reenters Bob and Willa’s lives with merciless force, deploying troops from his immigration taskforce on Baktan Cross, the sanctuary city where Bob and Willa have been laying low in the 16 years since Pat became Bob and baby Charlene, Willa, as the two went on the lam. —Rory Doherty, Time, 26 Sep. 2025

Ana, a rebellious 19-year-old from Barcelona, is sent by her wealthy father to a Patronato facility overseen by the merciless Sister Socorro. —Callum McLennan, Variety, 22 Sep. 2025

But is my merciless game persona merely nurture, or does nature have something to do with it too? —Julie Beck, The Atlantic, 17 Sep. 2025

Here, under the merciless South Florida sun, seeds of hope were planted again Sunday with Vrabel’s first win. —Andrew Callahan, Boston Herald, 16 Sep. 2025

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