nounchiefly North American
Middle English (in the sense 'knock to the ground'): from Old French fondrer, esfondrer 'submerge, collapse', based on Latin fundus 'bottom, base'
It is easy to confuse the words founder and flounder, not only because they sound similar but also because the contexts in which they are used overlap. Founder means, in its general and extended use, ‘fail or come to nothing, sink out of sight’ (the scheme foundered because of lack of organizational backing). Flounder, on the other hand, means ‘struggle, move clumsily, be in a state of confusion’ (new recruits floundering about in their first week).