Urim (û'rim), and Thummim (thŭm'-mim), light and perfection. Denote some part of the high priest's apparel. When Aaron was arrayed, Moses himself put the Urim and Thummin into the breastplate. Exodus 1:28-30, Leviticus 8:8. Nowhere in Scripture are the Urim and Thummim described, and we do not know what they really were.