difficult to accomplish; demanding considerable mental effort and skill; "the arduous work of preparing a dictionary"
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"
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
(usually followed by `to') having the necessary means or skill or know-how or authority to do something; "able to swim"; "she was able to program her computer"; "we were at last able to buy a car"; "able to get a grant for the project"
having inherent physical or mental ability or capacity; "able to learn"; "human beings are able to walk on two feet"; "Superman is able to leap tall buildings"
have the skills and qualifications to do things well; "able teachers"; "a capable administrator"; "children as young as 14 can be extremely capable and dependable"
having a strong healthy body; "an able seaman"; "every able-bodied young man served in the army"
threatening or foreshadowing evil or tragic developments; "a baleful look"; "forbidding thunderclouds"; "his tone became menacing"; "ominous rumblings of discontent"; "sinister storm clouds"; "a sinister smile"; "his threatening behavior"; "ugly black clouds"; "the situation became ugly"
deadly or sinister; "the Florida eagles have a fierce baleful look"
wishing or appearing to wish evil to others; arising from intense ill will or hatred; "a gossipy malevolent old woman"; "failure made him malevolent toward those who were successful"
filled with shade; "the shady side of the street"; "the surface of the pond is dark and shadowed"; "we sat on rocks in a shadowy cove"; "cool umbrageous woodlands"