hedgehog

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. 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.
2. n. Any of several spiny animals, such as the porcupine, that are similar to the hedgehog.
3. n. A well fortified military position.
4. n. An antisubmarine weapon consisting of several rows of mortar-like dischargers positioned to fire in a circular pattern ahead of a ship.
5. n. An obstacle used against tanks and landing craft, consisting of three crossed iron bars welded or bolted together.

Century Dictionary and Cyclopedia

1. n. In zoology, an insectivorous animal of the family Erinaceidæ and genus Erinaceus, of which there are several species. The common European hedgehog, Erinaceus europæus, is about 9 inches long; the body is covered above with spines, and the animal can roll itself into a ball bristling in every direction. This it accomplishes by means of a very highly developed and specialized panniculus carnosus, or fleshy layer beneath the skin, which when the body-is flexed acts as a sphincter, like the string which puckers the mouth of a bag. See cut under Erinaceus.
2. n. One of several other animals characterized by numerous spines. A Madagascan insectivorous animal of the family Centetidæ and any of the genera Centetes, Ericulus, and Hemicentetes. Otherwise known as tenrec.
3. n. In botany, a plant with echinate fruits. The name is used especially (often in the plural) for Medicago Echinus (M. intertexta), a native of Italy and Greece, the seeds of which are armed with short spines. It has also been given to Erinacea pungens (Anthyllis erinacea), a leguminous plant growing in Spain; to Ranunculus arvensis, a northern species; to Echinaria capitata, a grass of southern Europe; and to Hydnum erinaceus (also called hedgehog-hydnum), a fungus with tough elastic pileus, and very long straight hymeneal spines, growing on the trunks of oak- and beech-trees. Also hedgehog-plant.
4. n. A kind of dredging-machine consisting of a series of spades fixed to the periphery of a cylinder, used for loosening mud, silt, etc., so that it may be carried off by the current.
5. n. In Scotch mining, a broken strand or wire of a rope torn out while in motion and drawn up into a bundle.
6. n. In electricity, same as hedgehog-transformer.

Wiktionary

1. n. Small mammal, of the subfamily Erinaceinae, characterized by its spiny back and by its habit of rolling itself into a ball when attacked.
2. n. A type of moveable military barricade made from crossed logs or steel bars, laced with barbed wire, used to damage or impede tanks and vehicles; Czech hedgehog.
3. n. The nickname for a spigot mortar-type of depth charge weapon from World War II that simultaneously fires a number of explosives into the water to create a pattern of underwater explosions intended to attack submerged submarines.
4. n. Australia A type of chocolate cake (or slice), somewhat similar to an American brownie.

GNU Webster's 1913

1. n. (Zoöl.) A small European insectivore (Erinaceus Europæus), and other allied species of Asia and Africa, having the hair on the upper part of its body mixed with prickles or spines. It is able to roll itself into a ball so as to present the spines outwardly in every direction. It is nocturnal in its habits, feeding chiefly upon insects.
2. n. (Zoöl.), U.S The Canadian porcupine.
3. n. (Bot.) A species of Medicago (Medicago intertexta), the pods of which are armed with short spines; -- popularly so called.
4. n. A form of dredging machine.
5. n. (Elec.) A variety of transformer with open magnetic circuit, the ends of the iron wire core being turned outward and presenting a bristling appearance, whence the name.
6. n. (Mil.) a defensive obstacle having pointed barbs extending outward, such as one composed of crossed logs with barbed wire wound around them, or a tangle of steel beams embedded in concrete used to impede or damage landing craft on a beach; also, a position well-fortified with such defensive obstacles.

WordNet 3.0

1. n. small nocturnal Old World mammal covered with both hair and protective spines
2. n. relatively large rodents with sharp erectile bristles mingled with the fur