contagious vs catching

contagious is not a noun while catching is a noun.

Word	Noun	Adjective	Verb	Adverb
contagious	No	Yes	No	No
catching	Yes	Yes	No	No

As adjectives, contagious and catching are synonyms defined as:

contagious and catching: (of disease) capable of being transmitted by infection

Other synonyms of contagious include communicable, contractable, transmissible, transmittable.

contagious (noun)	catching (noun)
	(baseball) playing the position of catcher on a baseball team
	the act of detecting something; catching sight of something
	becoming infected

contagious (adjective)	catching (adjective)
(of disease) capable of being transmitted by infection	(of disease) capable of being transmitted by infection
easily diffused or spread as from one person to another