Adjective
without frets
Source: WordNetAmong the advantages to unfretted instruments are flexibility in tuning (the temperament can be easily altered) and the ability to play any music exactly as written without concern for "bad" notes. Source: Internet
Disadvantages include a smaller volume, even though many or most unfretted instruments tend to be significantly larger than fretted instruments; and many more strings to keep in tune. Source: Internet
Fretting Large five-octave unfretted clavichord by Paul Maurici, after J.A. Hass Since the string vibrates from the bridge only as far as the tangent, multiple keys with multiple tangents can be assigned to the same string. Source: Internet
Singing and unfretted stringed instruments The human voice is among the most pitch-flexible instruments in common use. Source: Internet
Such instruments are referred to as unfretted whereas instruments using the same strings for several notes are called fretted. Source: Internet
The unfretted stringed instruments from the violin family (the violin, the viola, the cello and the double bass) are quite flexible in the way pitches can be adjusted. Source: Internet