Synonyms of onerous

1 Syllable

hard, ter, harsh, trying

2 Syllables

heavy, grueling, troublous, pressing, grievous, painful, plodding, upstream, taxing, grave, hard-won, serious, strenuous, grinding, carking, arduous, galling, weighty, dragger, tiring, crushing

3 Syllables

laborious, demanding, rigorous, disturbing, distressing, backbreaker, perturbing, unwieldy, austere, toilsome, effortful, difficult, irksome, ballbuster, exhausting, severe, backbreaking, fatiguing, headache, ponderous, unsettling, merciless, upsetting, vexatious, exigent, heightened, exacting

4 Syllables

excessive, oppressive, boresome, difficile, burdensome, responsible, troublesome, cumbersome, formidable, tiresome, embittering, overtaxing, depressive

5 Syllables

intolerable, enervative, superincumbent, overpowering