The baby is fast asleep in the crib.
fast asleep
idiomSleeping, in a deep sleep.
Origin
disputed originThe 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.
When I checked on the children after the long trip, they were already fast asleep in their beds.
Despite the thunder rattling the windowpanes, the exhausted traveler remained fast asleep, undisturbed by the violent storm outside.
- 01
asleep at the switch
Neglectful of an important task, responsibility, or opportunity.
- 02
come thick and fast
To arrive rapidly in large groups.
- 03
dead asleep
Sleeping in a deep sleep
- 04
fall asleep
To be affected by paresthesia; to go numb.
- 05
fast and furious
Rapid and energetic.
- 06
fast sheet
A hotel or similar establishment catering to prostitutes.
- 07
fast times
A period of time characterized by quickly-paced activity, especially involving extravagant or risky conduct, sexual behavior, or other exciting events.
- 08
go nowhere fast
To fail to make any progress.