Fast asleep
Fast asleep adjective - Sleeping deeply.
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Synonyms for Fast asleep
Inactive and fast asleep are semantically related. In some cases you can use "Inactive" instead an adjective phrase "Fast asleep".
Inactive
Inactive adjective - Slow to move or act.
Fast asleep and inactive are semantically related. Sometimes you can use "Fast asleep" instead an adjective "Inactive".
Cite this Source
Inactive and Fast asleep. (2016). Retrieved 2026, August 02, from https://thesaurus.plus/related/fast_asleep/inactive
Fast asleep & Inactive. N.p., 2016. Web. 02 Aug. 2026. <https://thesaurus.plus/related/fast_asleep/inactive>.
Inactive or Fast asleep. 2016. Accessed August 02, 2026. https://thesaurus.plus/related/fast_asleep/inactive.
Google Ngram Viewer shows how "fast asleep" and "inactive" have occurred on timeline