obnoxious vs offensive

obnoxious is not a noun while offensive is a noun.

Word	Noun	Adjective	Verb	Adverb
obnoxious	No	Yes	No	No
offensive	Yes	Yes	No	No

obnoxious (noun)	offensive (noun)
	the action of attacking an enemy

obnoxious (adjective)	offensive (adjective)
causing disapproval or protest	unpleasant or disgusting especially to the senses
	causing anger or annoyance
	for the purpose of attack rather than defense
	morally offensive
	violating or tending to violate or offend against
	causing or able to cause nausea