Possible Definitions:
1. Apparatus (pl. ) of Apparatus
2. Apparatus (n.) Things provided as means to some end.
3. Apparatus (n.) Hence: A full collection or set of implements, or utensils, for a given duty, experimental or operative; any complex instrument or appliance, mechanical or chemical, for a specific action or operation; machinery; mechanism.
4. Apparatus (n.) A collection of organs all of which unite in a common function; as, the respiratory apparatus.