Real Dictionary

double bass
variable noun: A double bass is the largest instrument in the violin family. You play the double bass with a bow while standing up and holding it upright in front of you.

double bass in American English
the largest and deepest-toned instrument of the violin family (formerly, of the viol family), with a range of approximately three octaves
noun: the largest instrument of the violin family, having three or, usually, four strings, rested vertically on the floor when played

double bass in British English
noun: a stringed instrument, the largest and lowest member of the violin family. Range: almost three octaves upwards from E in the space between the fourth and fifth leger lines below the bass staff. It is normally bowed in classical music, but it is very commo

double-bass in British English
adjective: of or relating to an instrument whose pitch lies below that regarded as the bass