Source : Webster's Revised Unabridged Dictionary (1913)

Psaltery \Psal"ter*y\, n.; pl. {Psalteries}. [OE. sautrie, OF.
   psalterie, F. psalt['e]rion, L. psalterium psaltery, psalter,
   from Gr. ?, fr. ?. See {Psalm}, {Psalter}.]
   A stringed instrument of music used by the Hebrews, the form
   of which is not known.

         Praise the Lord with harp; sing unto him with the
         psaltery and an instrument of ten strings. --Ps.
                                                  xxxiii. 2.

Source : WordNet®

psaltery
     n : an ancient stringed instrument similar to the lyre or zither
         but having a trapezoidal sounding board under the strings