defy vs refuse

defy is not a noun while refuse is a noun.

Word	Noun	Adjective	Verb	Adverb
defy	No	No	Yes	No
refuse	Yes	No	Yes	No

As verbs, defy and refuse are synonyms defined as:

Other synonyms of defy include resist.

defy (noun)	refuse (noun)
	food that is discarded (as from a kitchen)

defy (verb)	refuse (verb)
challenge	show unwillingness towards
resist or confront with resistance	not accept as true
elude, especially in a baffling way	refuse to let have
	refuse entrance or membership
	elude, especially in a baffling way
	resist immunologically the introduction of some foreign tissue or organ