hoary vs biological science

hoary is not a noun while biological science is a noun.

Word	Noun	Adjective	Verb	Adverb
hoary	No	Yes	No	No
biological science	Yes	No	No	No

hoary (noun)	biological science (noun)
	the science that studies living organisms

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