|Origin:||ruth 'pity' (12-19 centuries), from rue|
so determined to get what you want that you do not care if you have to hurt other people in order to do it:
a ruthless dictator
They have shown a ruthless disregard for basic human rights.
determined and firm when making unpleasant decisions:
He ran the company with ruthless efficiency.
Throw away clothes you don't wear - be ruthless.
The uprising was ruthlessly suppressed.
—ruthlessness noun [uncountable]