hedgehog

from The American Heritage® Dictionary of the English Language, 5th Edition.

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

from The Century Dictionary.

• noun In electricity, same as hedgehog-transformer.
• noun In zoology, an insectivorous animal of the family Erinaceidæ and genus Erinaceus, of which there are several species.
• noun One of several other animals characterized by numerous spines.
• noun In botany, a plant with echinate fruits.
• noun 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.
• noun In Scotch mining, a broken strand or wire of a rope torn out while in motion and drawn up into a bundle.

from the GNU version of the Collaborative International Dictionary of English.

• noun (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.
• noun (Zoöl.), U.S The Canadian porcupine.
• noun (Bot.) A species of Medicago (Medicago intertexta), the pods of which are armed with short spines; -- popularly so called.
• noun A form of dredging machine.
• noun (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.
• noun (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.
• noun (Zoöl.) the hairy larvæ of several species of bombycid moths, as of the Isabella moth. It curls up like a hedgehog when disturbed. See Woolly bear, and Isabella moth.
• noun (Zoöl.) any spinose plectognath fish, esp. of the genus Diodon; the porcupine fish.
• noun (Bot.) a grass with spiny involucres, growing on sandy shores; burgrass (Cenchrus tribuloides).
• noun (Zoöl.) one of several West Indian rodents, allied to the porcupines, but with ratlike tails, and few quills, or only stiff bristles. The hedgehog rats belong to Capromys, Plagiodon, and allied genera.
• noun (Zoöl.) any spinose, marine, univalve shell of the genus Murex.
• noun (Bot.) a plant of the Cactus family, globular in form, and covered with spines (Echinocactus).
• noun See Diodon.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Small mammal, of the subfamily Erinaceinae, characterized by its spiny back and by its habit of rolling itself into a ball when attacked.
• noun 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.
• noun 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.
• noun Australia A type of chocolate cake (or slice), somewhat similar to an American brownie.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun small nocturnal Old World mammal covered with both hair and protective spines
• noun relatively large rodents with sharp erectile bristles mingled with the fur