retrogression vs regress

retrogression and regress both are nouns.

Word	Noun	Adjective	Verb	Adverb
retrogression	Yes	No	No	No
regress	Yes	No	Yes	No

As nouns, retrogression and regress are synonyms defined as:

Other synonyms of retrogression include regression, retroversion, reversion.

retrogression (noun)	regress (noun)
returning to a former state	returning to a former state
passing from a more complex to a simpler biological form	the reasoning involved when you assume the conclusion is true and reason backward to the evidence

retrogression (verb)	regress (verb)
	go back to bad behavior
	get worse or fall back to a previous condition
	go back to a previous state
	go back to a statistical means