a flag having three colored stripes (especially the French flag)
source: WordNet 3.0
The national French banner, of three colors, blue, white, and red, adopted at the first revolution.
source: Webster 1913
adjective satellite
having or involving three colors
Trichromatic vision. A trichromatic printing process. Trichromatic staining is the staining of tissue samples differentially in three colors. Tricolor plumage. A tricolor process in photography.