Origin
A room name that outlived the room
Fumoir is French for smoking room, from fumer, to smoke. The rooms emptied. The word did not.
The fumoir was a fixture of houses, clubs and liners built when smoking indoors was ordinary: a separate room, kept dark, furnished heavily, so that the smell and the noise stayed in one place.
What was practical turned out to be pleasant. Low light, absorbent fabric and deep chairs make people talk slowly and quietly. When the smoking stopped, the effect did not, and the word came loose from its own definition.
Today a fumoir is defined by atmosphere, not by function. That is precisely why it survived.
Word notes
Pronunciation
/foo-MWAHR/ — two syllables, stress on the second, final r soft.
Part of speech
Noun. Plural fumoirs. Increasingly used attributively: fumoir lighting, a fumoir corner.
Register
Informal when used of an aesthetic, neutral when used of an actual room.
Not to be confused with
Fumier (manure) and foyer. Neither is the vibe.