1. A collection of instruments adapted for a special purpose.
2. An instrument made up of several parts.
3. A group or system of glands, ducts, blood vessels, muscles, or other anatomic structures involved in the performance of some function.
The information shown above for apparatus is provided by Stedman's.
* Stedman's, part of Lippincott Williams & Wilkins, provide a comprehensive line of health-science publications for healthcare professionals and medical students.