catching vs contagious

catching is a noun but contagious is not a noun.

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

As adjectives, catching and contagious are synonyms defined as:

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

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

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

catching (adjective)	contagious (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