1. A tool, mechanical device, or piece of equipment used for precision work in science, medicine, or technology: "All surgical instruments must be sterilized."
2. A piece of equipment that measures or controls something; such as, position, speed (speedometer), or temperature.
3. An object used to produce music; for a performance or for private reasons; for example, a flute, a guitar, a piano, a drum, etc.
4. Someone or something used as a means of achieving a desired result or of accomplishing a particular purpose: "Some educators consider standardized testing as an instrument for improving the educational results in the schools."
5. An object that has been or could be used for a purpose: "On the street last night, he was struck from behind with a blunt instrument."
6. Etymology: from the late 13th century, "musical instrument", from Old French instrument, from Latin instrumentem, "a tool, an apparatus, furniture, a dress" or "a document"; from instruere, "to arrange, to furnish".

Any item used for the study of the positions, compositions, and movement of celestial bodies.

An electricity-measuring tool which indicates an ammeter or voltmeter, in contrast to an electric meter that records.

An instrument which depends for its operation on the reaction between the current in one or more movable coils and the current in one or more fixed coils.

A tool in which a beam of electrons is deflected by an electric or magnetic field (or both).

Usually the beam is made to strike a fluorescent screen so the deflection can be observed.

1. Instrumentation, including the speedometer, which is displayed with a digital readout rather than with the traditional analog gauges.
2. A digital instrument display for speed, miles, fuel level, fuel consumption clock, etc.

1. A musical instrument in which an audio signal is produced by a pickup or audio oscillator and amplified electronically to feed a loudspeaker; such as, in an electric guitar, electronic carillon, electronic organ, or electronic piano.
2. A musical device that generates sounds electronically.

1. A reference to an acoustical device; such as, a loudspeaker or microphone, which derives mechanical or electrical energy from the effect of an electrostatic field.
2. A meter which depends for its operation on the forces of attraction and repulsion between electrically charged bodies.

An apparatus which depends for its operation on the heating effect of an electric current.

An instrument that depends for its operation on the healing effect of a current.

Examples include the thermocouple, bolometric (a tool that detects and measures small amounts of thermal radiation), hot-wire, and hot-strip instruments.