Etymology of "flounder"

The Online Etymology Dictionary reads:

flounder (v.) 1590s, perhaps an alteration of founder (q.v.), influenced by Dutch flodderen "to flop about," or native verbs in fl- expressing clumsy motion.

Thus, the origin of flounder is not certain. However, after reading that dictionary entry, I wonder if flounder can be simply an embellishment of founder, where the sound unit fl might be used in order to carry a subliminal meaning of heavy movement, according to J. R. Firth's theory.

Can this origin be realistically considered?

Answer

In the following extract The word Word Detective explains why the two term fonder and flounder are often confused and comments on their possible origin. It appears that the noun "flounder" (a fish) and the verb flondev are not etymologically related , but the verb "flounder" is most likely an alteration of to fonder, derived from the assonance with other verbs like "blunder":

• The matter of “founder” versus “flounder” is exactly the sort of question my parents delighted in exploring, and in their Harper Dictionary of Contemporary Usage (1985), they delivered a concise verdict: “These two verbs are often confused and consequently misused. ‘Flounder’ means to ‘thrash about,’ as would an animal mired in mud. ‘Founder’ means to ‘fail completely, collapse or sink.’…”

The origin of "founder" is from French "fondrer":

• To begin at the beginning, the verb “to founder” means, in its basic sense, “to sink completely, collapse,” or, in an extended sense, “to fail utterly.” The source of “founder” was the Old French “fondrer,” meaning “submerge, send to the bottom,” and its ultimate root is the Latin “fundus,” meaning “bottom” (which also gave us the words “foundation,” “found” and “fundamental,” among others).

while the verb "flounder" probably is an alteration of "fonder" due to its assonance with other verbs:

• 
  

  “Flounder” as a verb is an odd bird. (The noun “flounder,” a kind of flat fish, is etymologically unrelated to the verb “to flounder”).

  
  


• 
  

  The verb “to flounder” is almost certainly an alteration of “to founder,” influenced by other verbs, such as “blunder,” depicting clumsy or frantic motion. When “flounder” first appeared in the 16th century, it meant “to stumble,” and later “to struggle clumsily.” A bit later on, it came to mean “to struggle along with great difficulty.”

  
  

But confusion between the two term persists:

• The confusion between “founder” and “flounder” arises when the extended figurative uses of the words converge. If clueless Jim has been promoted to sales manager and can’t handle the job, he may well “flounder” (struggle along) for a few months before he “founders” (fails) completely. In the example you gave, I would tend to think that “flounder” was actually the proper word, but without knowing the exact wording, it’s hard to be certain.