arduous
     adj 1: 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" [syn: {backbreaking}, {grueling}, {gruelling}, {hard},
             {heavy}, {laborious}, {punishing}, {toilsome}]
     2: taxing to the utmost; testing powers of endurance; "his
        final, straining burst of speed"; "a strenuous task";
        "your willingness after these six arduous days to remain
        here"- F.D.Roosevelt [syn: {straining}, {strenuous}]
     3: difficult to accomplish; demanding considerable mental
        effort and skill; "the arduous work of preparing a
        dictionary"
Source: WordNet® 2.0