Source : Webster's Revised Unabridged Dictionary (1913)

Prolong \Pro*long"\, v. t. [imp. & p. p. {Prolonged}; p. pr. &
   vb. n. {Prolonging}.] [F. prolonger, L. prolongare; pro
   before, forth + longus long. See {Long}, a., and cf.
   {Prolongate}, {Purloin}. ]
   1. To extend in space or length; as, to prolong a line.

   2. To lengthen in time; to extend the duration of; to draw
      out; to continue; as, to prolong one's days.

            Prolong awhile the traitor's life.    --Shak.

            The unhappy queen with talk prolonged the night.
                                                  --Dryden.

   3. To put off to a distant time; to postpone. --Shak.

Source : WordNet®

prolonged
     adj 1: relatively long in duration; tediously protracted; "a
            drawn-out argument"; "an extended discussion"; "a
            lengthy visit from her mother-in-law"; "a prolonged
            and bitter struggle"; "protracted negotiations" [syn:
            {drawn-out}, {extended}, {lengthy}, {protracted}]
     2: drawn out or made longer spatially; "Picasso's elongated Don
        Quixote"; "lengthened skirts are fashionable this year";
        "the extended airport runways can accommodate larger
        planes"; "a prolonged black line across the page" [syn: {elongated},
         {extended}, {lengthened}]
     3: (of illness) developing slowly or of long duration