The Collaborative International Dictionary of English v.0.48:

Redbreast \Red"breast`\ (-br?st`), n.
   1. (Zool.)
      (a) The European robin.
      (b) The American robin. See Robin.
      (c) The knot, or red-breasted snipe; -- called also robin
          breast, and robin snipe. See Knot.
          [1913 Webster]

   2. (Zool.) The long-eared pondfish. See Pondfish.
      [1913 Webster]

WordNet (r) 3.0 (2006):

redbreast
    n 1: small Old World songbird with a reddish breast [syn:
         robin, redbreast, robin redbreast, Old World robin,
         Erithacus rubecola]