Source : Webster's Revised Unabridged Dictionary (1913)

Flounder \Floun"der\, n. [Cf. Sw. flundra; akin to Dan. flynder,
   Icel. fly?ra, G. flunder, and perh. to E. flounder, v.i.]
   1. (Zo["o]l.) A flatfish of the family {Pleuronectid[ae]}, of
      many species.

   Note: The common English flounder is {Pleuronectes flesus}.
         There are several common American species used as food;
         as the smooth flounder ({P. glabra}); the rough or
         winter flounder ({P. Americanus}); the summer flounder,
         or plaice ({Paralichthys dentatus}), Atlantic coast;
         and the starry flounder ({Pleuronectes stellatus}).

   2. (Bootmaking) A tool used in crimping boot fronts.