[syn: elongated, extended, lengthened, prolonged]
The Collaborative International Dictionary of English v.0.48:
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. ]
   [1913 Webster]
   1. To extend in space or length; as, to prolong a line.
      [1913 Webster]
   2. To lengthen in time; to extend the duration of; to draw
      out; to continue; as, to prolong one's days.
      [1913 Webster]
            Prolong awhile the traitor's life.    --Shak.
      [1913 Webster]
            The unhappy queen with talk prolonged the night.
                                                  --Dryden.
      [1913 Webster]
   3. To put off to a distant time; to postpone. --Shak.
      [1913 Webster]
WordNet (r) 3.0 (2006):
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, prolonged, 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, prolonged]
Moby Thesaurus II by Grady Ward, 1.0:
36 Moby Thesaurus words for "prolonged":
   dragged out, dragging, drawn, drawn out, drawn-out, elongated,
   extended, interminable, languishing, lasting, lengthened, lengthy,
   lingering, long, long-continuing, long-drawn, long-drawn-out,
   long-pending, long-winded, longsome, marathon, overlong,
   prolongated, protracted, pulled, spun out, spun-out, straggling,
   strained, stretched, stretched out, stretched-out, strung out,
   taut, tense, tight