Synonyms of arduous

1 Syllable

tough, sheer, steep, harsh, trying, rough

2 Syllables

heavy, grueling, hi-tech, gasser, painful, steeper, upstream, taxing, hard-won, nagging, strenuous, steeping, sheerer, toilful, smarting, murder, dragger, tiring, steepest, uphill

3 Syllables

laborious, sanguineous, punishing, slaughterous, rigorous, murderous, effortful, toilsome, difficult, exhausting, severe, ballbuster, backbreaking, fatiguing, onerous, sobering, sideling, labored

4 Syllables

infestive, boresome, difficile, operose, burdensome, troublesome, formidable, complicated, declivitous, tiresome, unamusing, precipitous, overtaxing

5 Syllables

enervative

6 Syllables

energy-consuming