ARDUOUS

adj. 1 laborious, difficult, hard, tough, strenuous, onerous, burdensome, back-breaking, painful, Formal operose; tiring, exhausting, wearisome, fatiguing, taxing, gruelling, trying, formidable The Sherpas were well equipped for the arduous climb What an arduous task it is to read the proofs of a dictionary! 2 energetic, strenuous, vigorous Montrose made arduous efforts to reconstruct his army