biological defense vs American spelling

biological defense and American spelling both are nouns.

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

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