Source : Webster's Revised Unabridged Dictionary (1913)

Bystander \By"stand`er\, n. [By + stander, equiv. to stander-by;
   cf. AS. big-standan to stand by or near.]
   One who stands near; a spectator; one who has no concern with
   the business transacting.

         He addressed the bystanders and scattered pamphlets
         among them.                              --Palfrey.

   Syn: Looker on; spectator; beholder; observer.

Source : WordNet®

bystander
     n : a nonparticipant spectator