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

• affectless
• callous
• case-hardened
• cold-blooded
• compassionless
• desensitized
• hard
• hard-boiled
• hard-hearted
• heartless
• indurate
• inhuman
• inhumane
• insensate
• insensitive
• ironhearted
• obdurate
• pachydermatous
• pitiless
• remorseless
• ruthless
• slash-and-burn
• soulless
• stony
• stoney
• stonyhearted
• take-no-prisoners
• thick-skinned
• uncharitable
• unfeeling
• unmerciful
• unsparing
• unsympathetic

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

This time, his assignment takes him to Serbia, as he is tasked with assassinating the merciless General Mile Valstoria (Peter Linka). —Christopher Rudolph, People.com, 10 May 2025

That was 12 years ago, and yet the talk about him continues here, the ghosts live on, and with merciless frequency Lerro privately relives the fateful morning in which a vicious storm descended upon him with no warning. —Miami Herald Archives, Miami Herald, 8 May 2025

The Bear, an intense comedy-drama set in a merciless Chicago kitchen, racked up 21 Primetime Emmys across its first three seasons. —Ryan Coleman, EW.com, 6 May 2025

But too many backers of Israel can’t seem to imagine a reason besides antisemitic animus for impassioned opposition to Israel’s merciless war on the Gaza Strip. —Michelle Goldberg, Mercury News, 1 May 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