Adjective gruelling has 1 sense
  1. arduous, backbreaking, grueling, gruelling, hard, heavy, laborious, punishing, toilsome - characterized by toilsome 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"
    Antonym: effortless (indirect, via effortful)
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