The Collaborative International Dictionary of English v.0.48:

Cornish \Cor"nish\ (k?r"n?sh), a.
   Of or pertaining to Cornwall, in England.
   [1913 Webster]

   Cornish chough. See Chough.

   Cornish engine, a single-acting pumping engine, used in
      mines, in Cornwall and elsewhere, and for water works. A
      heavy pump rod or plunger, raised by the steam, forces up
      the water by its weight, in descending.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cornish \Cor"nish\, n.
   The dialect, or the people, of Cornwall.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Cornish
    adj 1: of or related to Cornwall or its people or the Cornish
           language
    n 1: a Celtic language spoken in Cornwall
    2: English breed of compact domestic fowl; raised primarily to
       crossbreed to produce roasters [syn: Cornish, Cornish
       fowl]