computing vs online

computing is a noun but online is not a noun.

Word	Noun	Adjective	Verb	Adverb
computing	Yes	No	No	No
online	No	Yes	No	No

computing (noun)	online (noun)
the procedure of calculating; determining something by mathematical or logical methods
the branch of engineering science that studies (with the aid of computers) computable processes and structures

computing (adjective)	online (adjective)
	connected to a computer network or accessible by computer
	on a regular route of a railroad or bus or airline system
	being in progress now