# at once

idiom · CEFR B2

Source: https://englishreference.com/idiom/at-once
Updated: 2026-04-22

## Meaning

to do something immediately or at the same time as something else.

## Examples

- Please finish your homework at once.
- The fire alarm rang, so everyone left the building at once.
- The king demanded that his advisors address the crisis at once, as the kingdom could not afford any further delay.

## Origin

From Middle English at ones, equivalent to at + once.

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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.