A tool made of wood and horsehair used to set the strings of a bowed string instrument in vibration. The bow was originally curved in the shape of a cycle, but it has been subject to many changes over time.a stick with horsehair stretched across it, used to play the strings of the violin and other string instruments. "to bow" means to play with the bow<br><br>A part of the tubing of an instrument of approximately semicircular shape