taxation vs regressive

taxation is a noun but regressive is not a noun.

Word	Noun	Adjective	Verb	Adverb
taxation	Yes	No	No	No
regressive	No	Yes	No	No

taxation (noun)	regressive (noun)
the imposition of taxes; the practice of the government in levying taxes on the subjects of a state
charge against a citizen's person or property or activity for the support of government
government income due to taxation

taxation (adjective)	regressive (adjective)
	opposing progress; returning to a former less advanced state
	(of taxes) adjusted so that the rate decreases as the amount of income increases