Source : Webster's Revised Unabridged Dictionary (1913)

Instrumentalist \In`stru*men"tal*ist\, n.
   One who plays upon an instrument of music, as distinguished
   from a vocalist.

Instrumentalism \In`stru*men"tal*ism\, n. (Philos.)
   The view that the sanction of truth is its utility, or that
   truth is genuine only in so far as it is a valuable
   instrument. -- {In`stru*men"tal*ist}, n.

         Instrumentalism views truth as simply the value
         belonging to certain ideas in so far as these ideas are
         biological functions of our organisms, and
         psychological functions whereby we direct our choices
         and attain our successes.                --Josiah
                                                  Royce.

Source : WordNet®

instrumentalist
     n : someone who plays a musical instrument (as a profession)
         [syn: {musician}, {player}]