fast asleep
Sleeping, in a deep sleep.
Meaning adapted from Wiktionary, available under CC BY-SA 4.0.
“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.”
disputed 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.
- 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.
Last updated August 10, 2026