The word 'instrument' can mean many different things depending on context. The most general synonyms include 'tool', 'apparatus', or 'gauge'.
Instrument
that may be the name of an instrument in another language.
Percussion Instrument.
They are called slides. They do not have another name.
A Graphometer, if you're talking about the instrument. Another word for semicircle is hemisphere.
reed organ
Instrument
One answer is here: http://www.cgconn.com/
A zithern is another name for a zither, a string instrument similar to a dulcimer.
Naarada does not use percussion instrument. He uses stringed instrument called " Tamboori" and another hand held instrument called "Chittige Taala"
The cluster is another name for the gauge assembly.
Instrument for holding another instrument is called " stand ".