Source : Webster's Revised Unabridged Dictionary (1913)

Porcupine \Por"cu*pine\, n. [OE. porkepyn, porpentine, OF.
   porc-espi, F. porc-['e]pic (cf. It. porco spino, porco
   spinoso, Sp. puerco espino, puerco espin, fr. L. porcus swine
   + spina thorn, spine). The last part of the French word is
   perhaps a corruption from the It. or Sp.; cf. F. ['e]pi ear,
   a spike of grain, L. spica. See {Pork}, {Spike} a large nail,
   {Spine}.]
   1. (Zo["o]l.) Any Old Word rodent of the genus {Hystrix},
      having the back covered with long, sharp, erectile spines
      or quills, sometimes a foot long. The common species of
      Europe and Asia ({Hystrix cristata}) is the best known.

   2. (Zo["o]l.) Any species of {Erethizon} and related genera,
      native of America. They are related to the true
      porcupines, but have shorter spines, and are arboreal in
      their habits. The Canada porcupine ({Erethizon dorsatus})
      is a well known species.

   {Porcupine ant-eater} (Zo["o]l.), the echidna.

   {Porcupine crab} (Zo["o]l.), a large spiny Japanese crab
      ({Acantholithodes hystrix}).

   {Porcupine disease} (Med.). See {Ichthyosis}.

   {Porcupine fish} (Zo["o]l.), any plectognath fish having the
      body covered with spines which become erect when the body
      is inflated. See {Diodon}, and {Globefish}.

   {Porcupine grass} (Bot.), a grass ({Stipa spartea}) with
      grains bearing a stout twisted awn, which, by coiling and
      uncoiling through changes in moisture, propels the
      sharp-pointed and barbellate grain into the wool and flesh
      of sheep. It is found from Illinois westward. See
      Illustration in Appendix.

   {Porcupine wood} (Bot.), the hard outer wood of the cocoa
      palm; -- so called because, when cut horizontally, the
      markings of the wood resemble the quills of a porcupine.

Source : WordNet®

porcupine fish
     n : spines become erect when the body is inflated; worldwide in
         warm waters [syn: {porcupinefish}, {Diodon hystrix}]