# fast asleep

idiom

Source: https://englishreference.com/idiom/fast-asleep
Updated: 2026-08-10

## Meaning

Sleeping, in a deep sleep.

## Examples

- The baby is fast asleep in the crib.
- The dog is fast asleep on the rug near the warm fireplace.
- My grandfather falls fast asleep in his chair every afternoon.
- When I checked on the children after the long trip, they were already fast asleep in their beds.
- I tried to wake my roommate for dinner, but he was fast asleep after working a double shift at the hospital.
- You can hear the cat snoring because she is fast asleep in the sunniest spot on the sofa.
- The security guard was fast asleep at his desk when the delivery driver arrived, so the packages were left outside the locked gate.
- Despite the thunder rattling the windowpanes, the exhausted traveler remained fast asleep, undisturbed by the violent storm outside.

## Origin

The original sense of fast in this term is the "firmly gripped or anchored" sense, thus as if stuck fast (embedded firmly) in sleep, but the homonymy with fast as in "quickly" happens to dovetail with the fact that a very tired person will archetypally fall asleep quickly, which tends to color this term with a connotation of falling asleep both quickly and deeply. (disputed)

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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.