hoary vs biology

hoary is not a noun while biology is a noun.

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

hoary (noun)	biology (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

hoary (adjective)	biology (adjective)
covered with fine whitish hairs or down
ancient
showing characteristics of age, especially having grey or white hair