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]

The Collaborative International Dictionary of English v.0.48:

Irish \I*rish"\, n. sing. & pl.
   1. pl. The natives or inhabitants of Ireland, esp. the Celtic
      natives or their descendants.
      [1913 Webster]

   2. The language of the Irish; also called Irish Gaelic or
      the Hiberno-Celtic.
      [1913 Webster +PJC]

   3. An old game resembling backgammon.
      [1913 Webster]

   get one's Irish up to become angry.
      [PJC] Irish American

WordNet (r) 3.0 (2006):

Irish
    adj 1: of or relating to or characteristic of Ireland or its
           people
    n 1: people of Ireland or of Irish extraction [syn: Irish,
         Irish people]
    2: whiskey made in Ireland chiefly from barley [syn: Irish,
       Irish whiskey, Irish whisky]
    3: the Celtic language of Ireland [syn: Irish, Irish Gaelic]