Source : Webster's Revised Unabridged Dictionary (1913)

Instrument \In"stru*ment\, n. [F. instrument, L. instrumentum.
   See {Instruct}.]
   1. That by means of which any work is performed, or result is
      effected; a tool; a utensil; an implement; as, the
      instruments of a mechanic; astronomical instruments.

            All the lofty instruments of war.     --Shak.

   2. A contrivance or implement, by which musical sounds are
      produced; as, a musical instrument.

            Praise him with stringed instruments and organs.
                                                  --Ps. cl. 4.

            But signs when songs and instruments he hears.
                                                  --Dryden.

   3. (Law) A writing, as the means of giving formal expression
      to some act; a writing expressive of some act, contract,
      process, as a deed, contract, writ, etc. --Burrill.

   4. One who, or that which, is made a means, or is caused to
      serve a purpose; a medium, means, or agent.

            Or useful serving man and instrument, To any
            sovereign state.                      --Shak.

            The bold are but the instruments of the wise.
                                                  --Dryden.

   Syn: Tool; implement; utensil; machine; apparatus; channel;
        agent.

Instrument \In"stru*ment\, v. t.
   To perform upon an instrument; to prepare for an instrument;
   as, a sonata instrumented for orchestra.

Source : WordNet®

instrument
     n 1: a device that requires skill for proper use
     2: the means whereby some act is accomplished; "my greed was
        the instrument of my destruction"; "science has given us
        new tools to fight disease" [syn: {tool}]
     3: a person used by another to gain an end [syn: {pawn}, {cat's-paw}]
     4: (law) a document that states some contractual relationship
        or grants some right [syn: {legal document}, {legal
        instrument}, {official document}]
     5: the semantic role of the entity (usually inanimate) that the
        agent uses to perform an action or start a process [syn: {instrumental
        role}]
     6: any of various devices or contrivances that can be used to
        produce musical tones or sounds [syn: {musical instrument}]

instrument
     v 1: equip with instruments for measuring, recording, or
          controlling
     2: write an instrumental score for [syn: {instrumentate}]
     3: address a legal document to

Source : Free On-Line Dictionary of Computing

instrument
     
         To install devices or instructions into hardware
        or software to monitor the operation of a system or component.
     
        (1996-05-22)