apparatus

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun An appliance or device for a particular purpose.
• noun An integrated group of materials or devices used for a particular purpose: synonym: equipment.
• noun The totality of means by which a designated function is performed or a specific task executed, as in a system of government.
• noun A political organization or an underground political movement.
• noun Physiology A group or system of organs that collectively perform a specific function or process.
• noun The critical and source material, usually including notes and a glossary, that accompanies a scholarly edition of a text.

from The Century Dictionary.

• An equipment of things provided and adapted as means to some end; especially, a collection, combination, or set of machinery, tools, instruments, utensils, appliances, or materials intended, adapted, and necessary for the accomplishment of some purpose, such as mechanical work, experimenting, etc.: as, chemical, philosophical, or surgical apparatus.
• Specifically— In physiology, a collection of organs which, though differing in structure, all minister to the same function: as, the respiratory apparatus; the digestive apparatus.
• A collection of materials for any literary work: as, critical apparatus for the study of the Greek text of the New Testament.

from the GNU version of the Collaborative International Dictionary of English.

• noun Things provided as means to some end.
• noun 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.
• noun (Physiol.) A collection of organs all of which unite in a common function.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The entirety of means whereby a specific production is made existent or task accomplished.
• noun A complex machine or instrument.
• noun An assortment of tools or instruments.
• noun A bureaucratic organization, especially one influenced by political patronage.
• noun firefighting A vehicle used for emergency response.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun equipment designed to serve a specific function
• noun (anatomy) a group of body parts that work together to perform a given function