see picul.-the bark of the oak, and some other trees, bruised and broken by a mill, for tanning hides; -- so called both before and after it has been used. called also tan bark.-a yellowish-brown color, like that of tan.-a brown color imparted to the skin by exposure to the sun; as, hands covered with tan.-of the color of tan; yellowish-brown.-to convert (the skin of an animal) into leather, as by usual process of steeping it in an infusion of oak or some other bark, whereby it is impregnated with tannin, or tannic acid (which exists in several species of bark), and is thus rendered firm, durable, and in some degree impervious to water.-to make brown; to imbrown, as by exposure to the rays of the sun; as, to tan the skin.-to get or become tanned.