/ ˌɪnstrəmenˈteɪʃn; NAmE / noun [ U ]
1.
a set of instruments used in operating a vehicle or a piece of machinery
2.
the way in which a piece of music is written for a particular group of instruments
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WORD ORIGIN
mid 19th cent.: from French , from instrumenter to instrument, from Latin instrumentum , from the verb instruere , from in- upon, towards + struere pile up.