Any of several small insectivorous mammals of the family Erinaceidae of Europe, Africa, and Asia, having the back covered with dense erectile spines and characteristically rolling into a ball for protection. Any of several spiny animals, such as the porcupine, that are similar to the hedgehog. A well fortified military position. An antisubmarine weapon consisting of several rows of mortar-like dischargers positioned to fire in a circular pattern ahead of a ship. An obstacle used against tanks and landing craft, consisting of three crossed iron bars welded or bolted together.