(Span. Guitarra), a musical instrument much used in Spain for accompanying songs. It is supposed to be of Arabian origin, and is the last relic of instruments of the late kind. There are different kinds of guitars—Spanish, French, and German; but the one most in use has six strings, generally tuned E, A, D, G, B, E, which chiefly belong to the bass register. Music for the guitar is written in the treble clef, though every note is an octave lower than represented. The guitar finger-board is furnished with frets, upon which the fingers of the left hand press down the strings, while these are struck by the fingers of the right hand. The Spanish and French guitars are nearly alike.