Unfretted clavichord
A design of early keyboard instruments (e.g. clavichord) where each key has its own string, rather than sharing strings with neighboring notes.
What it means
"Unfretted" describes clavichords in which each key has its own string or pair of strings. The term distinguishes this design from the "fretted" type, in which several neighboring keys share the same string, striking it at different points.
Musical use
On a fretted clavichord, the shared string does not allow simultaneous, independent tone color and tuning of neighboring notes, which placed tight limits on musical possibilities but saved on materials and construction effort. The unfretted clavichord solved this by giving each key its own string, allowing purer chords and more independent voice leading.
This more elaborate design became dominant especially in the eighteenth century, as the clavichord was increasingly used for more demanding polyphonic music. The unfretted clavichord should be distinguished from the harpsichord, which by design already has its own string for every pitch and therefore never faces this problem.