Unused or inactive
unoccupied, unemployed, jobless, workless, laid-off, uncultivated, untilled, fallow, vacant, deserted, not in use, not in operation, waste, barren, void, empty, abandoned, still, quiet, motionless, resting, stagnant, dormant, inert, passive, dead, untouched, rusty, gathering dust, dusty, down, out of action, at loose ends, out of a job, out of harness*, on the bum*; see also unemployed, unused 1.
Antonyms active*, busy, engaged.