1. (adjective) characterized by effort to the point of exhaustion; especially physical effort

• backbreaking
• grueling
• gruelling
• hard
• heavy
• laborious
• operose
• punishing
• toilsome

2. (adjective) taxing to the utmost; testing powers of endurance

• straining
• strenuous

1. (adjective) characterized by effort to the point of exhaustion; especially physical effort

• effortful

2. (adjective) taxing to the utmost; testing powers of endurance

• effortful

3. (adjective) difficult to accomplish; demanding considerable mental effort and skill

• difficult
• hard

1. (adjective) characterized by effort to the point of exhaustion; especially physical effort

• arduousness
• strenuousness
• burdensomeness
• heaviness
• onerousness
• oppressiveness
• hardness
• ruggedness
• labor
• labour
• toil
• laboriousness
• laboriousness
• laboriousness
• operoseness
• operoseness
• operoseness
• toilsomeness
• toilsomeness
• toilsomeness

2. (adjective) taxing to the utmost; testing powers of endurance

• arduousness
• arduousness
• strenuousness
• strenuousness
• nisus
• pains
• strain
• striving

3. (adjective) difficult to accomplish; demanding considerable mental effort and skill

• arduousness
• strenuousness