1. a tool or implement, especially one for delicate or scientific work:

〖通例修飾語を伴って〗 «…するための» (医療･実験などで使う)器具, 器械, 精密機器; 凶器 «to do, for doing»

e.g. a surgical instrument

e.g. writing instruments.

a thing used in pursuing an aim or policy; a means:

｟かたく｠ 〖通例単数形で〗 «…(するため)の» 手段, 施策 «of, for (doing)»

e.g. drama as an instrument of learning.

a person who is exploited or made use of:

媒介者, 手先; 機関

e.g. he was a mere instrument acting under coercion.

2. a measuring device used to gauge the level, position, speed, etc. of something, especially a motor vehicle or aircraft:

(飛行機などの) «…するための» 計器; 測定器 «to do, for doing»

e.g. a new instrument for measuring ozone levels

e.g. myriad instruments and switches.

3. (also musical instrument) an object or device for producing musical sounds:

楽器(musical instrument)

e.g. a percussion instrument.

4. a formal document, especially a legal one:

｟かたく｠ 法律文書, 証書

e.g. execution involves signature and unconditional delivery of the instrument.

verb with object

equip (something) with measuring instruments:

〈器具〉を取り付ける

e.g. engineers have instrumented rockets to study the upper atmosphere

e.g. a DC-8 aircraft instrumented as a flying laboratory.

Middle English: from Old French, or from Latin instrumentum ‘equipment, implement’, from the verb instruere ‘construct, equip’.