biology vs nodding

biology is a noun but nodding is not a noun.

Word	Noun	Adjective	Verb	Adverb
biology	Yes	No	No	No
nodding	No	Yes	No	No

biology (noun)	nodding (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)	nodding (adjective)
	having branches or flower heads that bend downward