Mezzanine

A mezzanine (; or in Italian, a mezzanino) is an intermediate floor in a building which is partly open to the double-height ceilinged floor below, or which does not extend over the whole floorspace of the building, a loft with non-sloped walls. However, the term is often used loosely for the floor above the ground floor, especially where a very high-ceilinged original ground floor has been split horizontally into two floors.
Mezzanines may serve a wide variety of functions. Industrial... meer