The Collaborative International Dictionary of English v.0.48:

Blackcap \Black"cap`\ (-k[a^]p`), n.
   1. (Zool.)
      (a) A small European song bird (Sylvia atricapilla),
          with a black crown; the mock nightingale.
      (b) An American titmouse (Parus atricapillus); the
          chickadee. Also called the black-cap chickadee.
          [1913 Webster]

   2. (Cookery) An apple roasted till black, to be served in a
      dish of boiled custard.
      [1913 Webster]

   3. The black raspberry.
      [1913 Webster]

WordNet (r) 3.0 (2006):

blackcap
    n 1: raspberry native to eastern North America having black
         thimble-shaped fruit [syn: black raspberry, blackcap,
         blackcap raspberry, thimbleberry, Rubus occidentalis]
    2: small black-headed European gull [syn: laughing gull,
       blackcap, pewit, pewit gull, Larus ridibundus]
    3: chickadee having a dark crown [syn: black-capped chickadee,
       blackcap, Parus atricapillus]
    4: small brownish-grey warbler with a black crown [syn:
       blackcap, Silvia atricapilla]