The Collaborative International Dictionary of English v.0.48:
Flounder \Floun"der\, n. [Cf. Sw. flundra; akin to Dan. flynder,
Icel. fly?ra, G. flunder, and perh. to E. flounder, v.i.]
1. (Zool.) A flatfish of the family Pleuronectid[ae], of
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.