Meaning

noun flesh of any of various American and European flatfish

noun any of various European and non-European marine flatfish

verb walk with great difficulty

originPossibly from the noun. Probably a blend of flounce + founder or a blend of founder + blunder or from Dutch flodderen (“wade”). See other terms beginning with fl, such as flutter, flitter, float, flap, flub, flip.

Etymology from Wiktionary, CC BY-SA 3.0