The term 'Violist's Need' is a crossword solution that refers to the BOW, which is a three-letter word. The BOW is an essential tool for a violist, as it is used to draw sound from the strings of the instrument. It is made of wood and horsehair, and is held in the right hand while the left hand moves the strings. The BOW is a crucial part of playing the viola, as it is the only way to produce sound from the instrument.