Fast
Fast adjective - Moving, proceeding, or acting with great speed.
Fast asleep and fast are semantically related. In some cases you can use "Fast asleep" instead an adjective "Fast".
Fast asleep
Fast asleep adjective - Sleeping deeply.
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Synonyms for Fast asleep
Fast and fast asleep are semantically related. Sometimes you can use "Fast" instead an adjective phrase "Fast asleep".
Mutual synonyms
Cite this Source
Fast asleep and Fast. (2016). Retrieved 2026, August 03, from https://thesaurus.plus/related/fast/fast_asleep
Fast & Fast asleep. N.p., 2016. Web. 03 Aug. 2026. <https://thesaurus.plus/related/fast/fast_asleep>.
Fast asleep or Fast. 2016. Accessed August 03, 2026. https://thesaurus.plus/related/fast/fast_asleep.
Google Ngram Viewer shows how "fast" and "fast asleep" have occurred on timeline