Source : Webster's Revised Unabridged Dictionary (1913)

Witness \Wit"ness\, v. i.
   To bear testimony; to give evidence; to testify. --Chaucer.

         The men of Belial witnessed against him. --1 Kings xxi.
                                                  13.

         The witnessing of the truth was then so generally
         attended with this event [martyrdom] that martyrdom now
         signifies not only to witness, but to witness to death.
                                                  --South.

Witness \Wit"ness\, v. t. [imp. & p. p. {Witnessed}; p. pr. &
   vb. n. {Witnessing}.]
   1. To see or know by personal presence; to have direct
      cognizance of.

            This is but a faint sketch of the incalculable
            calamities and horrors we must expect, should we
            ever witness the triumphs of modern infidelity. --R.
                                                  Hall.

            General Washington did not live to witness the
            restoration of peace.                 --Marshall.

   2. To give testimony to; to testify to; to attest.

            Behold how many things they witness against thee.
                                                  --Mark xv. 4.

   3. (Law) To see the execution of, as an instrument, and
      subscribe it for the purpose of establishing its
      authenticity; as, to witness a bond or a deed.

Witness \Wit"ness\, n. [AS. witness, gewitnes, from witan to
   know. [root]133. See {Wit}, v. i.]
   1. Attestation of a fact or an event; testimony.

            May we with . . . the witness of a good conscience,
            pursue him with any further revenge?  --Shak.

            If I bear witness of myself, my witness is not true.
                                                  --John v. 31.

   2. That which furnishes evidence or proof.

            Laban said to Jacob, . . . This heap be witness, and
            this pillar be witness.               --Gen. xxxi.
                                                  51, 52.

   3. One who is cognizant; a person who beholds, or otherwise
      has personal knowledge of, anything; as, an eyewitness; an
      earwitness. ``Thyself art witness I am betrothed.''
      --Shak.

            Upon my looking round, I was witness to appearances
            which filled me with melancholy and regret. --R.
                                                  Hall.

   4. (Law)
      (a) One who testifies in a cause, or gives evidence before
          a judicial tribunal; as, the witness in court agreed
          in all essential facts.
      (b) One who sees the execution of an instrument, and
          subscribes it for the purpose of confirming its
          authenticity by his testimony; one who witnesses a
          will, a deed, a marriage, or the like.

   {Privileged witnesses}. (Law) See under {Privileged}.

   {With a witness}, effectually; to a great degree; with great
      force, so as to leave some mark as a testimony. [Colloq.]

            This, I confess, is haste with a witness. --South.

Source : WordNet®

witness
     n 1: someone who sees an event and reports what happened [syn: {witnesser},
           {informant}]
     2: a close observer; someone who looks at something (such as an
        exhibition of some kind); "the spectators applauded the
        performance"; "television viewers"; "sky watchers
        discovered a new star" [syn: {spectator}, {viewer}, {watcher},
         {looker}]
     3: testimony by word or deed to your religious faith
     4: (law) a person who attests to the genuineness of a document
        or signature by adding their own signature [syn: {attestant},
         {attestor}, {attestator}]
     5: (law) a person who testifies under oath in a court of law

witness
     v 1: be a witness to
     2: perceive or be contemporaneous with; "We found Republicans
        winning the offices"; "You'll see a lot of cheating in
        this school"; "I want to see results"; "The 1960 saw the
        rebellion of the younger generation against established
        traditions"; "I want to see results" [syn: {find}, {see}]