| Word | Definitions | Synonyms |
|---|---|---|
| arduous | (adjective) difficult to accomplish; demanding considerable mental effort and skill | - |
| (adjective) characterized by effort to the point of exhaustion; especially physical effort | Synonyms: backbreaking, grueling, gruelling, hard, heavy, laborious, operose, punishing, toilsome | |
| (adjective) taxing to the utmost; testing powers of endurance | Synonyms: straining, strenuous |