A guitar without frets. It operates in the same manner as most other stringed instruments and traditional guitars, but does not have any frets to act as the lower end point (node) of the vibrating string. On a fretless guitar, the vibrating string length runs from the bridge, where the strings are attached, all the way up to the point where the fingertip presses the string down on the fingerboard.

Fretless guitars are fairly uncommon in most forms of Western music and generally limited to the electrified instruments due to decreased acoustic volume and sustain in fretless instruments. However, the fretless bass guitar has gained fairly widespread popularity due to the similarity in feel and sound to the acoustic double bass and many models of bass guitar can be found in fretless varieties.