current vs on-line

current is a noun but on-line is not a noun.

Word	Noun	Adjective	Verb	Adverb
current	Yes	Yes	No	No
on-line	No	Yes	No	No

current (noun)	on-line (noun)
a steady flow of a fluid (usually from natural causes)
dominant course (suggestive of running water) of successive events or ideas
a flow of electricity through a conductor

current (adjective)	on-line (adjective)
occurring in or belonging to the present time	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