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".