Webster's Revised Unabridged Dictionary · 1913

Mezzanine

Mezzanine , noun

[French mezzanine, Italian mezzanino, from mezzano middle, from mezzo middle, half. See Mezzo.]

1.
(a) (Architecture) Same as Entresol.
(b)
(Architecture) A partial story which is not on the same level with the story of the main part of the edifice, as of a back building, where the floors are on a level with landings of the staircase of the main house.
2.
A flooring laid over a floor to bring it up to some height or level.
3.
(Theater) A floor under the stage, from which various contrivances, as traps, are worked.
4.
The lowest balcony in a theater, or the forward part of the first balcony.