1. The installation and use of (electronic) instruments; the assembly of such instruments for a purpose; the design of how the instruments should be arranged.
An artifact (or system of artifacts) that is instrumental in accomplishing some end.

2. (specifically, measurement instruments) Any system of instruments and associated devices used for detecting, signaling, observing, measuring, controlling, or communicating attributes of a physical object or process.

2b. Facilities (or tools) that provide access to the attributes of managed resources, to retrieve or modify values of these attributes. Access to managed resources used by agents to respond to management requests.

In the 1960's, in rocket science [1], "instrumentation" is:

1. The installation and use of electronic, gyroscopic, and other instruments for the purpose of detecting, measuring, recording, telemetering, processing, or analyzing different values or quantities as encountered in the flight of a rocket or spacecraft.
2. The assemblage of such instruments in a rocket, spacecraft, or the like.
3. A special field of engineering concerned with the design, composition, and arrangement of such instruments.

In this context, "to instrument" means "to provide a vehicle or component with instrumentation"

The meaning therefore became focused on measurement instruments. Therefore, in electronics, "instrumentation" is:

- the use or application of instruments for observation, measurement or control
- Apparatus (often electronic) which is used for measurement or control; and for display of measurements or conditions
- method for collecting profiling data

This meaning focuses on "collecting information", as in programming: "the insertion of additional code into the program in order to collect information about program behaviour during program execution."

Use in Advertising (Marketing), example:

The company "NetQos" (Quality of Service, a feature of computer networking) offers a service which it calls "Network Instrumentation Design " It is NOT clear how this differs from the other services they offer, "Application Readiness Assessment" and "Network Performance Assessment".