a. [ L. arduus steep, high; akin to Ir. ard high, height. ] 1. Steep and lofty, in a literal sense; hard to climb. [ 1913 Webster ]

Those arduous paths they trod. Pope. [ 1913 Webster ]

2. Attended with great labor, like the ascending of acclivities; difficult; laborious; as, an arduous employment, task, or enterprise. [ 1913 Webster ]

Syn. -- Difficult; trying; laborious; painful; exhausting. -- Arduous, Hard, Difficult. Hard is simpler, blunter, and more general in sense than difficult; as, a hard duty to perform, hard work, a hard task, one which requires much bodily effort and perseverance to do. Difficult commonly implies more skill and sagacity than hard, as when there is disproportion between the means and the end. A work may be hard but not difficult. We call a thing arduous when it requires strenuous and persevering exertion, like that of one who is climbing a precipice; as, an arduous task, an arduous duty. “It is often difficult to control our feelings; it is still harder to subdue our will; but it is an arduous undertaking to control the unruly and contending will of others.” [ 1913 Webster ]

adv. In an arduous manner; with difficulty or laboriousness. [ 1913 Webster ]

n. The quality of being arduous; difficulty of execution. [ 1913 Webster ]