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

Cora, the granddaughter of a woman kidnapped from West Africa and sold into slavery, flees her captor’s plantation, plunging her into the book’s alternate steampunk reality where she is pursued by the merciless slave catcher Ridgeway. — David Faris, TheWeek, 16 Sep. 2026

But the movie very much belongs to Trinca and Bruni Tedeschi, just as Anna belongs to the merciless stranger. — David Rooney, HollywoodReporter, 8 Sep. 2026

More than 3,000 shows and a sizable cult following later, The Dark Room has evolved into a choose-your-own-adventure live action video game, presided over by Robertson as its obscene, merciless and incredibly quick-witted host. — Rebecca Rosman, NPR, 31 Aug. 2026

In Braun’s script, the merciless obstacle course of singlehood seems just absurd. — Faith Hill, The Atlantic, 14 Aug. 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