Dumb spinet

from The Collaborative International Dictionary of English v.0.48

Spinet \Spin"et\, n. [OF. espinete, F. ['e]pinette (cf. It.
   spinetta), fr. L. spina a thorn; -- so called because its
   quills resemble thorns. See {Spine}.] (Mus.)
   A keyed instrument of music resembling a harpsichord, but
   smaller, with one string of brass or steel wire to each note,
   sounded by means of leather or quill plectrums or jacks. It
   was formerly much used.
   [1913 Webster]

   {Dumb spinet}. (Mus.) See {Manichordon}.
      [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Manichord \Man"i*chord\, Manichordon \Man`i*chor"don\, [L.
   monochordon, Gr. ?; -- so called because it orig. had only
   one string. See {Monochord}.] (Mus.)
   The clavichord or clarichord; -- called also {dumb spinet}.
   [1913 Webster]