1. [n]  intermediate floor just above the ground floor
2. [n]  first or lowest balcony

MEZZANINE is a 9 letter word that starts with M.

1. \Mez"za*nine\, n. [F. mezzanine, It. mezzanino, fr.
   mezzano middle, fr. mezzo middle, half. See {Mezzo}.] (Arch.)
   (a) Same as {Entresol}.
   (b) 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. \Mez"za*nine\, n.
   1. A flooring laid over a floor to bring it up to some height
      or level.
   
   2. Also
   
   {mezzanine floor}. (Theat.) A floor under the stage, from
      which various contrivances, as traps, are worked.