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.). instrument board (or panel) a surface, esp. in a car or aeroplane, containing the dials etc. of measuring-devices.
[ ME f. OF instrument or L instrumentum (as INSTRUCT) ]