onerous
/ˈɒnəɹəs/adjective
Requiring so much effort that it feels like a heavy load; hard to bear.
Example sentences
- “Filling out all the paperwork by hand was an onerous task.”
- “Small businesses complained that the new rules were too onerous.”
Formal. From Latin onus, a burden, a word English also uses directly: the onus is on you to prove it.