Source : Webster's Revised Unabridged Dictionary (1913)

Tridacna \Tri*dac"na\, n. [L., pl., a kind of oysters, fr. Gr. ?
   eaten at three bites, ? tri- + ? to bite.] (Zo["o]l.)
   A genus of very large marine bivalve shells found on the
   coral reefs of the Indian and Pacific Oceans. One species
   ({T. gigas}) often weighs four or five hundred pounds, and is
   sometimes used for baptismal fonts. Called also {paw shell},
   and {fountain shell}.

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.