Meaning of “merciless” - Learner’s Dictionary

merciless

adjective uk us /ˈmɜːsɪləs/

cruel, or showing no kindness:

a merciless attack
She was merciless in her criticism of his work.
mercilessly adverb

He was mercilessly bullied by the older boys.

(Definition of “merciless” from the Cambridge Learner’s Dictionary © Cambridge University Press)