Source : Webster's Revised Unabridged Dictionary (1913)

Penthouse \Pent"house`\, n. [A corruption of pentice.]
   A shed or roof sloping from the main wall or building, as
   over a door or window; a lean-to. Also figuratively. ``The
   penthouse of his eyes.'' --Sir W. Scott.

Penthouse \Pent"house`\, a.
   Leaning; overhanging. ``Penthouse lid.'' --Shak. ``My
   penthouse eyebrows.'' --Dryden.

Source : WordNet®

penthouse
     n : an apartment located on the top floors of a building