VIOLA, or ALTO VIOLA, an instrument of the violin kind, larger than an ordinary violin, and furnished with four strings, the third and fourth of these being covered with silver-plated copper wire. It originated from the viola di basso, one of the ancient set of viols used in concerts. The English call it the tenor-violin, or simply the tenor. Its name of alto-violin is derived from its music being written in the alto-clef on the third line of the stave. It is tuned C, G, D, A, an octave above the violoncello. For its compass, and use in orchestra, &c., see MUSIC.