laborious or oppressive (of a contract, lease, etc) having or involving burdens or obligations that counterbalance or outweigh the advantages
WordReference Random House Learner's Dictionary of American English © 2025
on•er•ous /ˈɑnərəs, ˈoʊnər-/USA pronunciation
adj.
WordReference Random House Unabridged Dictionary of American English © 2025- being a burden;
troublesome:an onerous task.
on•er•ous
(on′ər əs, ō′nər-),USA pronunciation adj.
on′er•ous•ly, adv.
on′er•ous•ness, o•ne•ros•i•ty
(ō′nə ros′i tē),USA pronunciation n.
- burdensome, oppressive, or troublesome; causing hardship:onerous duties.
- having or involving obligations or responsibilities, esp. legal ones, that outweigh the advantages:an onerous agreement.
- Latin onerōsus, equivalent. to oner- (stem of onus) burden + -ōsus -ous
- Middle English 1350–1400
- 1.See corresponding entry in Unabridged heavy, crushing, grievous; irksome, galling.
Collins Concise English Dictionary © HarperCollins Publishers::
'onerous' also found in these entries (note: many are not synonyms or translations):