Source : Webster's Revised Unabridged Dictionary (1913)

Giant \Gi"ant\, n. [OE. giant, geant, geaunt, OF. jaiant, geant,
   F. g['e]ant, L. gigas, fr. Gr. ?, ?, from the root of E.
   gender, genesis. See {Gender}, and cf. {Gigantic}.]
   1. A man of extraordinari bulk and stature.

            Giants of mighty bone and bold emprise. --Milton.

   2. A person of extraordinary strength or powers, bodily or
      intellectual.

   3. Any animal, plant, or thing, of extraordinary size or
      power.

   {Giant's Causeway}, a vast collection of basaltic pillars, in
      the county of Antrim on the northern coast of Ireland.

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

   {Giant cell}. (Anat.) See {Myeloplax}.

   {Giant clam} (Zo["o]l.), 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} (Zo["o]l.), 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} (Zo["o]l.), a very large aquatic
      salamander ({Megalobatrachus maximus}), found in Japan. It
      is the largest of living Amphibia, becoming a yard long.
      

   {Giant squid} (Zo["o]l.), one of several species of very
      large squids, belonging to {Architeuthis} and allied
      genera. Some are over forty feet long.

Source : WordNet®

giant
     adj : of great mass; huge and bulky; "a jumbo jet"; "jumbo shrimp"
           [syn: {elephantine}, {gargantuan}, {jumbo}]

giant
     n 1: any creature of exceptional size
     2: a person of exceptional importance and reputation [syn: {colossus},
         {behemoth}, {heavyweight}, {titan}]
     3: an unusually large enterprise; "Walton built a retail giant"
     4: a very large person; impressive in size or qualities [syn: {hulk},
         {heavyweight}, {whale}]
     5: someone or something that is abnormally large and powerful
        [syn: {goliath}, {behemoth}, {monster}, {colossus}]
     6: an imaginary figure of superhuman size and strength; appears
        in folklore and fair tales
     7: a very bright star of large diameter and low density
        (relative to the Sun) [syn: {giant star}]