Noun
A part or decoration of the breastplate of the high priest among the ancient Jews, by which Jehovah revealed his will on certain occasions. Its nature has been the subject of conflicting conjectures.
Source: Webster's dictionaryAaron and his successors as high priest were given control over the Urim and Thummim by which the will of God could be determined (Exodus 28:30). Source: Internet
According to the Jewish Encyclopedia Abiathar was deposed from office when he was deserted by the Holy Spirit without which the Urim and Thummin could not be consulted. Source: Internet
However, some would claim that divination is indeed practiced in the Bible, such as in Exodus 28, when the Urim and Thummim are mentioned. Source: Internet