Late 17th century. From French rubican (adjective, of a horse's coat) having white patches, (noun) horse's coat with white patches, horse whose coat has white patches, alteration (probably by association with rubicond, since the remainder of the horse's coat is often reddish in colour) of †rabican from Italian rabicano and its etymon Spanish rabicano (although this is apparently first attested later: 1561) from rabo tail + cano white, white-haired.