What does onerous mean?
Onerous describes something that imposes a heavy or difficult burden, especially a task, duty, requirement, or set of conditions. The word is especially common in legal, business, administrative, and academic writing, where it can identify obligations that are difficult to meet because they involve considerable time, effort, expense, or complexity. For example, a contract may contain onerous clauses, or a workplace may introduce onerous safety requirements. Onerous is more forceful and formal than difficult and often suggests that the burden is not merely temporary or minor. Its Latin root, onus, means “burden,” which explains the word’s sense of weight and difficulty. Although it can sometimes sound negative, it is normally precise and neutral in meaning rather than emotional, making it useful when describing requirements that are substantively demanding.
adjectiveInvolving a heavy or difficult burden; demanding considerable effort, effort, or expense. It is especially used for tasks, duties, requirements, and conditions that are burdensome or difficult to satisfy.
- Involving or imposing a heavy, difficult, or burdensome task, obligation, requirement, or condition.
"The committee faced the onerous task of reviewing hundreds of applications in only two weeks."
"The new regulations impose onerous costs on small businesses."
"She was unwilling to accept the onerous terms of the agreement."
Onerous comes from the Latin onus, meaning “burden,” so the word literally points to something weighty that must be carried.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does onerous come from?
Onerous comes from the Latin adjective onerosus, meaning “burdensome” or “heavy,” which was formed from onus, meaning “burden.” English usage developed through French onéreux before the word was established in English in the late sixteenth century. The root also appears in related forms such as onus and onerosity.
Related word forms
How onerous is actually used
This is a formal word, common in legal, administrative, business, and academic contexts. It usually suggests that the burden is substantial, complicated, or inconvenient rather than merely unpleasant.
Easily confused with onerous
Onerous means difficult or burdensome, whereas erroneous means mistaken or based on error.