- British informal a hot and stale atmosphere; fug
C19: back formation from frowsty musty, stuffy, variant of frowzy
Examples from the Web for frowst
Lying in bed in the morning when there is no First School is a "frowst."
By a subtle law of association, an armchair is also a "frowst."
The places are heated but not aired, and the smell is horrid; but they seem to revel in "frowst."My War Experiences in Two Continents
If you want to keep warm while travelling (to frowst, as the open air school calls it) do not get in with well-bred Englishwomen.Dangerous Ages
I was pretty bad myself, but managed to move about all the time, for the frowst in my cabin would have sickened a hippo.Greenmantle