cru·el / ˈkroōəl/ • adj. (-el·er, -el·est; Brit. -el·ler, -el·lest) causing pain or suffering: people who are cruel to animals. ∎  having or showing a sadistic disregard for the pain or suffering of others: a cruel face.DERIVATIVES: cru·el·ly adv.

cruel be cruel to be kind act towards someone in a way which seems harsh but will ultimately be of benefit; often with reference to Hamlet's explanation of his outspoken condemnation to his mother of her second marriage.
cruel and unusual punishment punishment which is seen to exceed the bounds of what is regarded as an appropriate penal remedy for a civilized society; it derives from the Eighth Amendment (1791) to the Constitution of the United States.

cruel XIII. — (O)F. :- L. crūdēlis, rel. to crūdus CRUDE.
So cruelty XIII. — OF. crualté (mod. cruauté) :- Rom. *crūdālitās, for L. crūdēlitās.