The Collaborative International Dictionary of English v.0.48:

Giant \Gi"ant\, a.
   Like a giant; extraordinary in size, strength, or power; as,
   giant brothers; a giant son.
   [1913 Webster]

   Giant cell. (Anat.) See Myeloplax.

   Giant clam (Zool.), a bivalve shell of the genus
      Tridacna, esp. T. gigas, which sometimes weighs 500
      pounds. The shells are sometimes used in churches to
      contain holy water.

   Giant heron (Zool.), a very large African heron (Ardeomega
      goliath). It is the largest heron known.

   Giant kettle, a pothole of very large dimensions, as found
      in Norway in connection with glaciers. See Pothole.

   Giant powder. See Nitroglycerin.

   Giant puffball (Bot.), a fungus (Lycoperdon giganteum),
      edible when young, and when dried used for stanching
      wounds.

   Giant salamander (Zool.), a very large aquatic salamander
      (Megalobatrachus maximus), found in Japan. It is the
      largest of living Amphibia, becoming a yard long.

   Giant squid (Zool.), one of several species of very large
      squids, belonging to Architeuthis and allied genera.
      Some are over forty feet long.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Squid \Squid\ (skw[i^]d), n. [Cf. Squirt.]
   1. (Zool.) Any one of numerous species of ten-armed
      cephalopods having a long, tapered body, and a caudal fin
      on each side; especially, any species of Loligo,
      Ommastrephes, and related genera. See Calamary,
      Decacerata, Dibranchiata.
      [1913 Webster]

   Note: Some of these squids are very abundant on the Atlantic
         coast of North America, and are used in large
         quantities for bait, especially in the cod fishery. The
         most abundant of the American squids are the northern
         squid (Ommastrephes illecebrosus), ranging from
         Southern New England to Newfoundland, and the southern
         squid (Loligo Pealii), ranging from Virginia to
         Massachusetts.
         [1913 Webster]

   2. A fishhook with a piece of bright lead, bone, or other
      substance, fastened on its shank to imitate a squid.
      [1913 Webster]

   Flying squid, Giant squid. (Zool.) See under Flying,
      and Giant.

   Squid hound (Zool.), the striped bass.
      [1913 Webster]

WordNet (r) 3.0 (2006):

giant squid
    n 1: largest mollusk known about but never seen (to 60 feet
         long) [syn: architeuthis, giant squid]