the.com/upright bass

means The large wooden stand-up string bass used in jazz, bluegrass, and folk music, played by plucking or bowing — the deep rumbling backbone under the band.

from Also called the double bass or contrabass, it descends from the viol family of the Renaissance and Baroque eras, not the violin family, despite looking like a giant violin — which is why its sloped shoulders differ from a cello's. 'Upright' simply distinguishes it from its 20th-century offspring, the electric bass guitar, which lies flat and gets played sitting down or slung over a shoulder. The name is plain description: the instrument stands upright, taller than the person playing it.