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]

The Collaborative International Dictionary of English v.0.48:

Pinefinch \Pine"finch`\ (p[imac]n"f[i^]nch`), n. (Zool.)
   (a) A small American bird (Spinus spinus syn. Chrysomitris
       spinus); -- called also pine siskin, and American
       siskin.
   (b) The pine grosbeak.
       [1913 Webster]

WordNet (r) 3.0 (2006):

pine siskin
    n 1: small finch of North American coniferous forests [syn:
         pine siskin, pine finch, Spinus pinus]