irony vs sarcastic

irony is a noun but sarcastic is not a noun.

Word	Noun	Adjective	Verb	Adverb
irony	Yes	No	No	No
sarcastic	No	Yes	No	No

irony (noun)	sarcastic (noun)
incongruity between what might be expected and what actually occurs
a trope that involves incongruity between what is expected and what occurs
witty language used to convey insults or scorn

irony (adjective)	sarcastic (adjective)
	expressing or expressive of ridicule that wounds