A device used to make an impression (usually on clay or wax) that showed ownership, authenticity, or agreement. Ancient seals consisted of a piece of hard material (stone, ivory, or wood) having engraved letters or designs in reverse. A seal is used figuratively for something stamped as authentic, or as a mark of possession, or as something that is hidden or secret.​—Ex 28:11; Ne 9:38; Re 5:1; 9:4.