Plural of tom; perfections, i.e. (techn.) One of the epithets of the objects in the high-priest's breastplate as an emblem of complete Truth -- Thummim.
KJV: And thou shalt put in the breastplate of judgment the Urim and the Thummim; and they shall be upon Aaron's heart, when he goeth in before the LORD: and Aaron shall bear the judgment of the children of Israel upon his heart before the LORD continually.
NASB: "You shall put in the breastpiece of judgment the Urim and the Thummim, and they shall be over Aaron's heart when he goes in before the LORD; and Aaron shall carry the judgment of the sons of Israel over his heart before the LORD continually.
KJV: And of Levi he said, Let thy Thummim and thy Urim be with thy holy one, whom thou didst prove at Massah, and with whom thou didst strive at the waters of Meribah;
NASB: Of Levi he said, "Let Your Thummim and Your Urim belong to Your godly man, Whom You proved at Massah, With whom You contended at the waters of Meribah;