zith·er 
(z
ĭth
ər, z
ĭth-) also
zith·ern (-
ərn)
n. A musical instrument composed of a flat sound box with about 30 to 40 strings stretched over it and played horizontally with the fingertips, a plectrum, or a bow, or set into vibration by the wind, as in the Aeolian harp.
[German, from Middle High German *zitter, from Old High German zitera, from Latin cithara, cithara, from Greek kitharā.]
zither·ist n.

zither