a. 费力的, 努力的, 险峻的

Arduous \Ar"du*ous\ (?; 135), a. [L. arduus steep, high; akin to
Ir. ard high, height.]
1. Steep and lofty, in a literal sense; hard to climb.

Those arduous paths they trod. --Pope.

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

Syn: Difficult; trying; laborious; painful; exhausting.

Usage: {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.''