n. & v.
--n.
1. a tool or implement, esp. for delicate or scientific work.
2 (in full musical instrument) a device for producing musical sounds by vibration, wind, percussion, etc.
3 a a thing used in performing an action (the meeting was an instrument in his success). b a person made use of (is merely their instrument).
4 a measuring-device, esp. in an aeroplane, serving to determine its position in darkness etc.
5 a formal, esp. legal, document.
--v.tr.
1. arrange (music) for instruments.
2 equip with instruments (for measuring, recording, controlling, etc.).
Phrases and idioms:
instrument board (or panel) a surface, esp. in a car or aeroplane, containing the dials etc. of measuring-devices.
Etymology: ME f. OF instrument or L instrumentum (as INSTRUCT)