biological science vs mouthless

biological science is a noun but mouthless is not a noun.

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

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

biological science (adjective)	mouthless (adjective)
	having no mouth or mouthlike opening