/ ˈruːθləs; NAmE / adjective
( disapproving ) ( of people or their behaviour ) hard and cruel; determined to get what you want and not caring if you hurt other people :
a ruthless dictator
The way she behaved towards him was utterly ruthless.
He has a ruthless determination to succeed.
► ruth·less·ly adverb
► ruth·less·ness noun [ U ]
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WORD ORIGIN
Middle English : from ruth feeling of pity, distress or grief + -less .