a tool or implement, especially one for delicate or scientific work.
a surgical instrument
a measuring device used to gauge the level, position, speed, etc., of something, especially a motor vehicle or aircraft.
In low visibility, they help guide pilots to the runway as we transition from flying on the aircraft's instruments to a visual landing.
an object or device for producing musical sounds.
a percussion instrument
a formal document, especially a legal one.
execution involves signature and unconditional delivery of the instrument