the largest and deepest-toned instrument of the violin family (formerly, of the viol family), with a range of approximately three octaves
The largest bowed stringed instrument in the modern orchestra, also used frequently in jazz ensembles, especially played pizzicato. The double bass, usually considered a member of the violin family, is tuned in fourths and has the sloping shoulders and flat back characteristic of the viols. It has a deep range, going as low as three octaves below middle C. Also called bass fiddle, bass viol, bull fiddle, contrabass, string bass.
Origin of double bassdouble, tuned an octave lower than (from the fact that a string or pipe that is twice the length of another gives a pitch an octave lower) + bass2.