The Collaborative International Dictionary
Rubican
Rubican \Ru"bi*can\, a. [F.]
Colored a prevailing red, bay, or black, with flecks of white
or gray especially on the flanks; -- said of horses.
--Smart.
Wiktionary
rubican
a. (context of a horse English) Coloured mostly red, bay, or black, with flecks of white or grey especially on the flanks.