overcome vs defeat

overcome is not a noun while defeat is a noun.

Word	Noun	Adjective	Verb	Adverb
overcome	No	No	Yes	No
defeat	Yes	No	Yes	No

As verbs, overcome and defeat are synonyms defined as:

Other synonyms of overcome include get the better of.

overcome (noun)	defeat (noun)
	an unsuccessful ending to a struggle or contest
	the feeling that accompanies an experience of being thwarted in attaining your goals

overcome (verb)	defeat (verb)
get on top of; deal with successfully	win a victory over
overcome, usually through no fault or weakness of the person that is overcome	thwart the passage of
win a victory over
overcome, as with emotions or perceptual stimuli