The Collaborative International Dictionary of English v.0.48:

Siskin \Sis"kin\, n. [Dan. sisgen; cf. Sw. siska, G. zeisig, D.
   sijsje; of Slav. origin; cf. Pol. czy[zdot].] (Zool.)
   (a) A small green and yellow European finch (Spinus spinus,
       or Carduelis spinus); -- called also aberdevine.
   (b) The American pinefinch (Spinus pinus); -- called also
       pine siskin. See Pinefinch.
       [1913 Webster]

   Note: The name is applied also to several other related
         species found in Asia and South America.
         [1913 Webster]

   Siskin green, a delicate shade of yellowish green, as in
      the mineral torbernite.
      [1913 Webster]

WordNet (r) 3.0 (2006):

siskin
    n 1: small yellow-and-black Eurasian finch with a sharp beak
         [syn: siskin, Carduelis spinus]