DIADEM, in heraldry, is applied to certain circles, or rims, serving to inclose the crowns of sovereign princes, and to bear the globe and cross, or the flower deuces for their crest. The crowns of sovereigns are bound, some with a greater, and some with a less number of diadems.—The bandage about the heads of Moors on shields is also called diadem, in blazoning.