instrument /ˈɪnstɹəmənt/noun 7verb 3forms 3 noun7 •A measuring or displaying device.The instrument detected an increase in radioactivity. •a device built to give out music when someone blows, strikes or presses itThe violinist was a master of her instrument. •A tool, implement used for manipulation or measurement.The dentist set down his tray of instruments.The scientist recorded the temperature with a thermometer, but wished he had a more accurate instrument. •[usually plural] Ellipsis of flight instrument.Flight within clouds must be made by reference to your instruments. •A means or agency for achieving an aspect. •(figurative) A person used as a mere tool for achieving a goal.Or useful serving man and instrument, / To any sovereign state. — 1596 •A legal document, such as a contract, deed, trust, mortgage, power, indenture, or will, or any of a class of negotiable ones (which can be exchanged for value or money).A bond indenture is the instrument that gives a bond its value.Negotiable instruments are the foundation of the debt markets. verb3 •To apply measuring devices. •To perform upon an instrument; to prepare for an instrument.a sonata instrumented for orchestra •To devise, conceive, cook up, plan. formsinstrumented · instrumenting · instruments