idle vs ineffective

idle is a noun but ineffective is not a noun.

Word	Noun	Adjective	Verb	Adverb
idle	Yes	Yes	Yes	No
ineffective	No	Yes	No	No

idle (noun)	ineffective (noun)
the state of an engine or other mechanism that is idling

idle (adjective)	ineffective (adjective)
not in action or at work	not producing an intended effect
silly or trivial	lacking in power or forcefulness
not in active use	lacking the ability or skill to perform effectively; inadequate
lacking a sense of restraint or responsibility
not having a job
not yielding a return
without a basis in reason or fact

idle (verb)	ineffective (verb)
run disconnected or idle
be idle; exist in a changeless situation