ARDUOUS
arduous
(adjective) difficult to accomplish; demanding considerable mental effort and skill; “the arduous work of preparing a dictionary”
arduous, backbreaking, grueling, gruelling, hard, heavy, laborious, operose, punishing, toilsome
(adjective) characterized by 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”
arduous, straining, strenuous
(adjective) 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
Source: WordNet® 3.1
Etymology
Adjective
arduous (comparative more arduous, superlative most arduous)
Needing or using up much energy; testing powers of endurance.
(obsolete) burning; ardent
• Cary
Difficult or exhausting to traverse.
Synonyms
• burdensome, demanding, exhausting, fatiguing, laborious, onerous, strenuous, strugglesome, wearisome
Source: Wiktionary
Ar"du*ous, a. Etym: [L. arduus steep, high; akin to Ir. ard high,
height.]
1. Steep and lofty, in a literal sense; hard to climb.
Those arduous pats 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.
– 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."
Source: Webster’s Unabridged Dictionary 1913 Edition