Apparatus \Ap"pa*ratus\, n.; pl. Apparatus, also rarely Apparatuses. [L., from apparare, apparatum, to prepare; ad + prepare to make ready.]

1. Things provided as means to some end.

2. 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.

3. (Physiol.) A collection of organs all of which unite in a common function; as, the respiratory apparatus.

Source: Webster's Revised Unabridged Dictionary (1913)