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" arduousbackbreakinggruelinggruellinghardheavylaboriousoperosepunishingtoilsome
resulting in punishment "the king imposed a punishing tax" punishing