Source : Webster's Revised Unabridged Dictionary (1913)

Redstart \Red"start`\ (-st?rt`), n. [Red + start tail.]
   (Zo["o]l.)
   (a) A small, handsome European singing bird ({Ruticilla
       ph[oe]nicurus}), allied to the nightingale; -- called
       also {redtail}, {brantail}, {fireflirt}, {firetail}. The
       black redstart is {P.tithys}. The name is also applied to
       several other species of {Ruticilla} amnd allied genera,
       native of India.
   (b) An American fly-catching warbler ({Setophaga ruticilla}).
       The male is black, with large patches of orange-red on
       the sides, wings, and tail. The female is olive, with
       yellow patches.

Source : WordNet®

redstart
     n 1: flycatching warbler of eastern North America the male having
          bright orange on sides and wings and tail [syn: {American
          redstart}, {Setophaga ruticilla}]
     2: European songbird with a reddish breast and tail; related to
        Old World robins [syn: {redtail}]