From 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
many species.
[1913 Webster]
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).
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2. (Bootmaking) A tool used in crimping boot fronts.
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From The Collaborative International Dictionary of English v.0.48:
Flounder \Floun"der\, v. i. [imp. & p. p. Floundered; p. pr. &
vb. n. Floundering.] [Cf. D. flodderen to flap, splash
through mire, E. flounce, v.i., and flounder the fish.]
To fling the limbs and body, as in making efforts to move; to
struggle, as a horse in the mire, or as a fish on land; to
roll, toss, and tumble; to flounce.
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They have floundered on from blunder to blunder. --Sir
W. Hamilton.
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From The Collaborative International Dictionary of English v.0.48:
Flounder \Floun"der\, n.
The act of floundering.
[1913 Webster]