biology vs free-living

biology is a noun but free-living is not a noun.

Word	Noun	Adjective	Verb	Adverb
biology	Yes	No	No	No
free-living	No	Yes	No	No

biology (noun)	free-living (noun)
the science that studies living organisms
all the plant and animal life of a particular region
characteristic life processes and phenomena of living organisms

biology (adjective)	free-living (adjective)
	not parasitic on another organism