Also sometimes known as the 4-string guitar, this is a slightly smaller, 4-string relative of the steel-strung acoustic guitar or electric guitar. The instrument was initially developed in its acoustic form by Gibson and Martin so that players of the 4-string tenor banjo could double on guitar.

A tenor guitar is normally made in the shape of a guitar, or sometimes with a lute-like pear shaped body or, more rarely, with a round banjo-like wooden body. They can be acoustic, electric or both and they can come in the form of flat top or archtop wood-bodied, metal-bodied resonator, or solid-bodied instruments. Tenor guitars normally have a scale length similar to that of the tenor banjo and octave mandolin of between 21 and 23 inches (53 and 58 cm).