WordWeb Online

1. Resulting in punishment
   "the king imposed a punishing tax"
    
2. Characterized by effort to the point of exhaustion; especially physical effort
   "set a punishing pace";
   - arduous, backbreaking, grueling [US], gruelling [Brit, Cdn], hard, heavy, laborious, operose, toilsome, killing [informal]

1. Impose a penalty on; inflict punishment on
   "we had to punish the dog for soiling the floor again";
   - penalize, penalise [Brit], sanction
    
2. Treat or be treated in a bad, harsh or unfair way; be subject to a bad outcome or be beaten
   "Are states being punished for their successful efforts in attracting business?"

See also: effortful

Encyclopedia: Punishing