biological defense vs biological defence

biological defense and biological defence both are nouns.

Word	Noun	Adjective	Verb	Adverb
biological defense	Yes	No	No	No
biological defence	Yes	No	No	No

As nouns, biological defense and biological defence are synonyms defined as:

biological defense and biological defence: procedures involved in taking defensive measures against attacks using biological agents

Other synonyms of biological defense include biodefence, biodefense.

biological defense (noun)	biological defence (noun)
procedures involved in taking defensive measures against attacks using biological agents	procedures involved in taking defensive measures against attacks using biological agents