【Inactive】 , 【idle】 ,  【inert】 ,  【passive】 ,  【supine】  mean not engaged in work or activity.

【Inactive】 is applicable to anyone or to anything that for any reason is not currently in action, in operation, in use, or at work.

【Idle】  (see also VAIN 1 ) applies chiefly to persons who are without occupation or not busy at the moment, but it is also applicable to their powers or to the implements they use.

【Inert】 as applied to a thing (as matter, a substance, or a drug) implies inherent lack of power to set itself in motion or by itself to produce a given or understood effect. As applied to persons or their activities,  【inert】 suggests inherent or habitual indisposition to activity or extreme difficulty in stimulating or setting in motion.

【Passive】 implies immobility or a lack of a positive reaction when subjected to external driving or impelling forces or to provocation. In an extended sense  【passive】 often implies submissiveness without such positive responsiveness as would help the person or side that attacks or seeks to impose its will, but it still more often implies a failure to be provoked to action or resistance.

【Supine】 implies abject or cowardly inertia or passivity usually as a result of apathy or indolence.