(an instance of) extreme cruelty

crudity, savagery

great cruelty

cruel treatment

(an act of) readiness to cause pain or suffering to others

brutality, harshness

(an instance of) the absence of pity; cruelty

lack of compassion

the deep and long-lasting feeling that one has after being ignored, injured or insulted

bitterness, hatefulness

deliberate harm to a person in return for harm done

retaliation for wrong, grievance