founder vs flop

founder and flop both are nouns.

Word	Noun	Adjective	Verb	Adverb
founder	Yes	No	Yes	No
flop	Yes	No	Yes	Yes

As verbs, flop is a hyponym of founder; that is, flop is a word with a more specific, narrower meaning than founder:

Other hyponyms of founder include go off, implode, buckle, crumple, break, sink, slide down, slump.

As verbs, founder and flop are synonyms defined as:

Other synonyms of founder include fall flat, fall through.

founder (noun)	flop (noun)
a person who founds or establishes some institution	the act of throwing yourself down; collapse; sink
a worker who makes metal castings	a complete failure
inflammation of the laminated tissue that attaches the hoof to the foot of a horse	someone who is unsuccessful
	an arithmetic operation performed on floating-point numbers

founder (verb)	flop (verb)
break down, literally or metaphorically	fall suddenly and abruptly
sink below the surface	fall loosely
stumble and nearly fall	fail utterly; collapse
fail utterly; collapse

founder (adverb)	flop (adverb)
	with a flopping sound
	completely