viola da gamba

Generic name for the members of the viol family, all of which, small or large, are played on or between the legs. Unlike the violin family they have flat backs, sloping shoulders, six strings, and frets. The smaller instruments of the family gradually went out of use in the course of the 17th century, but the bass was retained as a solo instrument and for continuo playing. Hence in the 18th century viola da gamba normally means the bass viol. Examples of its use are Johann Sebastian Bach's three sonatas with harpsichord and the obbligatos in the St Matthew Passion. All the members of the family have been successfully revived in modern times.