arduous
adjective(ar-du-ous)
taxing to the utmost; testing powers of endurance
Examples:
Your willingness after these six arduous days to remain here.
arduous
adjective(ar-du-ous)
characterized by effort to the point of exhaustion; especially physical effort
Examples:
Worked their arduous way up the mining valley.
arduous
adjective(ar-du-ous)
difficult to accomplish; demanding considerable mental effort and skill
Examples:
The arduous work of preparing a dictionary.