Source : Webster's Revised Unabridged Dictionary (1913)

Clavichord \Clav"i*chord\, n. [F. clavicorde, fr. L. clavis key
   + chorda string.] (Mus.)
   A keyed stringed instrument, now superseded by the
   pianoforte. See {Clarichord}.

Source : WordNet®

clavichord
     n : an early stringed instrument like a piano but with more
         delicate sound