Idle (noun) = the state of being nothing to do.
eg: I am idle at home during the school holiday. (which is not true by the way)
Idle (adjective) = not working, unemployed, free, nothing to do, not in use
eg: Mr. John is idle ever since he has been fired by his boss 3 weeks ago.
Idle (verb without object) = to pass time doing nothing
eg: Sam idled in the shopping morning the whole day, yesterday.
Idle (verb with object) = to make idle.
eg: I waited in the car while idling the engine.