Synonyms of punishing

1. punish, penalize, penalise: usage: impose a penalty on; inflict punishment on; "The students were penalized for showing up late for class"; "we had to punish the dog for soiling the floor again"

1. punishing: usage: resulting in punishment; "the king imposed a punishing tax"
2. arduous, backbreaking, grueling, gruelling, hard, heavy, laborious, operose, punishing, toilsome, effortful (vs. effortless): usage: characterized by effort to the point of exhaustion; especially physical effort; "worked their arduous way up the mining valley"; "a grueling campaign"; "hard labor"; "heavy work"; "heavy going"; "spent many laborious hours on the project"; "set a punishing pace"