flounder | founder

(1) To fail or sink is to founder,
(2) to have any type of difficulty at all is to flounder.

Example -
Foundering is a type of floundering.

Etymology -

(1) The verb founder derives from the Old French fondrer, fall to the bottom, which in turn derives from the Latin fundus, bottom.
(2) The verb flounder was coined by modifying founder.

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