chemical defense vs American spelling

chemical defense and American spelling both are nouns.

Word	Noun	Adjective	Verb	Adverb
chemical defense	Yes	No	No	No
American spelling	Yes	No	No	No

chemical defense (noun)	American spelling (noun)
procedures involved in taking defensive measures against attacks using chemical agents	English orthography used in the United States (characterized by 'analyze', 'center', 'usable')