Source : Webster's Revised Unabridged Dictionary (1913)

Porterhouse \Por"ter*house\, n.
   A house where porter is sold.

   {Porterhouse steak}, a steak cut from a sirloin of beet,
      including the upper and under part.

Source : WordNet®

porterhouse
     n : large steak from the thick end of the short loin containing
         a T-shaped bone and large piece of tenderloin [syn: {porterhouse
         steak}]