n. A round or flat wedge of iron passed through a hole in the inner end of a bolt to prevent its withdrawal when a strain is placed on it.n. In medieval armor, a clasp or catch serving to hold the helm, or in some cases the beaver or the mentonnière, to the gorgerin or breastplate in front.Nautical, to secure by a forelock, as a bolt.n. The lock of hair that grows from the fore part of the head; a prominent or somewhat detached lock above the forehead, especially of a horse.