ruthless

UK: /ˈruːθləs/ US: /ˈruθlɪs/ ,(ro̅o̅th′lis)

WordReference Random House Learner's Dictionary of American English © 2025

ruth•less /ˈruθlɪs/   adj. 

1. without pity or compassion;
   cruel;
   merciless:
   a ruthless desire to win at all costs.

ruth•less•ly, adv.: 

The general pressed his men ruthlessly ahead.

ruth•less•ness, n. [uncountable]

WordReference Random House Unabridged Dictionary of American English © 2025

ruth•less  (ro̅o̅th′lis), adj. 

1. without pity or compassion;
   cruel;
   merciless:
   a ruthless tyrant.

• 1300–50; Middle English; see ruth, -less

ruth′less•ly, adv. 
ruth′less•ness, n. 
Synonyms

unrelenting, adamant, relentless. See cruel. 

Collins Concise English Dictionary © HarperCollins Publishers::

ruthless / ˈruːθlɪs/ adjective

1. feeling or showing no mercy; hardhearted

ˈruthlessly adverb

ˈruthlessness noun