The Collaborative International Dictionary of English v.0.48:

Irish \I"rish\, a. [AS. [imac]risc, fr. [imac]ras the Irish. Cf.
   Aryan, Erse.]
   Of or pertaining to Ireland or to its inhabitants; produced
   in Ireland.
   [1913 Webster]

   Irish elk. (Zool.) See under Elk.

   Irish moss.
   (a) (Bot.) Carrageen.
   (b) A preparation of the same made into a blanc mange.

   Irish poplin. See Poplin.

   Irish potato, the ordinary white potato, so called because
      it is a favorite article of food in Ireland.

   Irish reef, or Irishman's reef (Naut.), the head of a
      sail tied up.

   Irish stew, meat, potatoes, and onions, cut in small pieces
      and stewed.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Irish potato
    n 1: an edible tuber native to South America; a staple food of
         Ireland [syn: potato, white potato, Irish potato,
         murphy, spud, tater]