Merriam-Webster Collegiate Dictionary - roan

 I. adjective  Etymology: Middle French, from Old Spanish ~o  Date: 1530 having the base color (as red, black, or brown) muted and lightened by admixture of white hairs a ~ horse a ~ calf  II. noun  Date: 1580  1. an animal (as a horse) with a ~ coat — usually used of a red ~ when unqualified  2. the color of a ~ horse — used especially when the base color is red  III. noun  Etymology: origin unknown  Date: 1818 sheepskin tanned with sumac and colored and finished to imitate morocco