bacteria vs Gram-negative

bacteria is a noun but Gram-negative is not a noun.

Word	Noun	Adjective	Verb	Adverb
bacteria	Yes	No	No	No
Gram-negative	No	Yes	No	No

bacteria (noun)	Gram-negative (noun)
(microbiology) single-celled or noncellular spherical or spiral or rod-shaped organisms lacking chlorophyll that reproduce by fission; important as pathogens and for biochemical properties; taxonomy is difficult; often considered to be plants

bacteria (adjective)	Gram-negative (adjective)
	(of bacteria) being of or relating to a bacterium that does not retain the violet stain used in Gram's method