# onus

/ˈoʊnəs/ (US) · /ˈəʊnəs/ (UK) · CEFR C1 · Noun

Source: https://englishreference.com/word/onus
Updated: 2026-05-18

## Definition

the duty or responsibility to do something. It is the part of a task that you must handle yourself.

For teachers: the duty or burden of proof, responsibility, or action. Often used in legal or formal contexts to describe the obligation placed on a specific party.

## Examples

- The onus is on the defendant to prove their innocence.
- In many legal cases, the onus of proof lies with the prosecution to establish the defendant's guilt beyond a reasonable doubt.
- The onus of maintaining the historical site fell upon the local council, which struggled to secure the necessary funding for its preservation despite public interest.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.