mouthless vs biology

mouthless is not a noun while biology is a noun.

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

mouthless (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

mouthless (adjective)	biology (adjective)
having no mouth or mouthlike opening