- 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"
- 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
- difficult to accomplish; demanding considerable mental effort and skill; "the arduous work of preparing a dictionary"
- (arduously) in an arduous manner; "they worked arduously"
- (arduousness) extreme effortfulness
- Scinax arduous is a species of frog in the Hylidae family. It is endemic to Brazil. Its natural habitat is subtropical or tropical moist lowland forests. It is threatened by habitat loss.
- Needing or using up much energy; testing powers of endurance; this sense) Difficult or exhausting to traverse
- difficult or demanding
- Involving or requiring strenuous effort; difficult and tiring. “Pine trees flanked the road, fewer than I remembered and many of them bare, but it was good to see trees again after the arduous drive through the Khyber Pass” (233).