| Main Entry: | |
| Part of Speech: | adjective |
| Definition: | hard, difficult |
| Synonyms: | arduous, backbreaking, burdensome, effortful, fatiguing, forced, heavy, herculean, labored, onerous, operose, ponderous, rough go, stiff, strained, strenuous, tiresome, toilsome, tough, tough job, wearing, wearisome, wicked* |
| Antonyms: | easy, effortless, facile, simple, trivial |
| Main Entry: | arduous |
| Part of Speech: | adjective |
| Definition: | difficult, hard to endure |
| Synonyms: | backbreaking, burdensome, exhausting, fatiguing, formidable, grueling, harsh, heavy, labored, laborious, murder, no picnic, onerous, painful, punishing, rigorous, rough, severe, strenuous, taxing, tiring, toilsome, tough, troublesome, trying, uphill |
| Antonyms: | easy, facile, motivating |
| Main Entry: | assiduous |
| Part of Speech: | adjective |
| Definition: | hard-working |
| Synonyms: | active, attentive, busy, constant, diligent, eager beaver, exacting, grinding, indefatigable, industrious, laborious, persevering, plugging, scrupulous, sedulous, steady, studious, unflagging, untiring, whiz, zealous |
| Antonyms: | lazy, neglectful, negligent |
| Main Entry: | backbreaking |
| Part of Speech: | adjective |
| Definition: | strenuous |
| Synonyms: | arduous, exhausting, grueling, hard, laborious, punishing, taxing, toilsome, wearisome |
| Main Entry: | difficult |
| Part of Speech: | adjective |
| Definition: | hard on someone; hard to do |
| Synonyms: | Gargantuan, Herculean, ambitious, arduous, backbreaker, bothersome, burdensome, challenging, crucial, demanding, difficile, easier said than done, effortful, exacting, formidable, galling, hard-won, heavy, immense, intricate, irritating, labored, laborious, no picnic, not easy, onerous, operose, painful, problem, problematic, prohibitive, rigid, severe, stiff, strenuous, titanic, toilsome, tough, troublesome, trying, unyielding, uphill, upstream, wearisome |
| Antonyms: | calm, easy, free, manageable, plain, simple, uncomplicated |
| Main Entry: | diligent |
| Part of Speech: | adjective |
| Definition: | persevering, hard-working |
| Synonyms: | active, assiduous, attentive, busy, careful, conscientious, constant, eager, eager beaver, earnest, grind*, indefatigable, industrious, laborious, occupied, operose, painstaking, persistent, persisting, pertinacious, plugging, sedulous, steadfast, studious, tireless, unflagging, unrelenting, untiring |
| Antonyms: | inactive, indifferent, languid, lazy, lethargic, negligent |
| Main Entry: | formidable |
| Part of Speech: | adjective |
| Definition: | difficult, overwhelming |
| Synonyms: | all-powerful, arduous, awesome, ballbuster, challenging, colossal, dismaying, effortful, great, hard, impressive, indomitable, intimidating, labored, laborious, mammoth, mighty, murder*, onerous, overpowering, powerful, puissant, rough go, rough*, staggering, strenuous, tall order, toilsome, tough proposition, tough*, tremendous, uphill |
| Antonyms: | easy, not hard, pleasant, trivial |
| Main Entry: | grueling |
| Part of Speech: | adjective |
| Definition: | difficult, taxing |
| Synonyms: | arduous, backbreaking, brutal, chastening, crushing, demanding, excruciating, exhausting, fatiguing, fierce, grinding, hairy*, hard, harsh, heavy*, laborious, punishing, racking, severe, stiff, strenuous, tiring, torturous, trying |
| Notes: | grueling means characterized by physical effort to the point of exhaustion; gruesome means shockingly repellent, inspiring horror |
| Antonyms: | easy, facile |
| Main Entry: | hard |
| Part of Speech: | adjective |
| Definition: | difficult, exhausting |
| Synonyms: | Herculean, arduous, backbreaking, bothersome, burdensome, complicated, demanding, difficile, distressing, effortful, exacting, fatiguing, formidable, grinding, hairy*, heavy*, intricate, involved, irksome, knotty, labored, laborious, mean, merciless, murder, onerous, operose, rigorous, rough, rugged, scabrous, serious, severe, slavish, sticky, strenuous, terrible, tiring, toilful, toilsome, tough, troublesome, unsparing, uphill battle, uphill, wearing, wearisome, wearying |
| Antonyms: | easy, facile, mild, simple |