The Collaborative International Dictionary of English v.0.48:

Tricolor \Tri"col`or\, n. [F. tricolore, drapeau tricolore a
   tricolored flag, fr. tricolore three-colored; tri (see
   Tri-) + L. color color.] [Written also tricolour.]
   [1913 Webster]
   1. The national French banner, of three colors, blue, white,
      and red, adopted at the first revolution.
      [1913 Webster]

   2. Hence, any three-colored flag.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tricolour
    n 1: a flag having three colored stripes (especially the French
         flag) [syn: tricolor, tricolour]