psychological medicine vs regression

psychological medicine and regression both are nouns.

Word	Noun	Adjective	Verb	Adverb
psychological medicine	Yes	No	No	No
regression	Yes	No	No	No

psychological medicine (noun)	regression (noun)
the branch of medicine dealing with the diagnosis and treatment of mental disorders	returning to a former state
	the relation between selected values of x and observed values of y (from which the most probable value of y can be predicted for any value of x)
	(psychiatry) a defense mechanism in which you flee from reality by assuming a more infantile state
	an abnormal state in which development has stopped prematurely