(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. We’ll have to be ruthless if we want to make this company more efficient. Word Origin Middle English: from ruth ‘feeling of pity, distress or grief’ + -less.Extra examples She was pretty ruthless about sacking people. He’s a violent, ruthless man who will stop at nothing. Like all great survivors, she has a ruthless streak. She was ruthless about chucking out weaklings. The way she behaved to him was utterly ruthless. We’ll have to be ruthless if we want to make this company more efficient.