The Collaborative International Dictionary of English v.0.48:

Tanager \Tan"a*ger\, n. [NL. tanagra, probably fr. Brazilian
   tangara.] (Zool.)
   Any one of numerous species of bright-colored singing birds
   belonging to Tanagra, Piranga, and allied genera. The
   scarlet tanager (Piranga erythromelas) and the summer
   redbird (Piranga rubra) are common species of the United
   States.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tanager
    n 1: any of numerous New World woodland birds having brightly
         colored males