Source : Webster's Revised Unabridged Dictionary (1913)

Dueling \Du"el*ing\, n.
   The act or practice of fighting in single combat. Also adj.
   [Written also {duelling}.]

Source : WordNet®

duel
     n 1: a prearranged fight with deadly weapons by two people
          (accompanied by seconds) in order to settle a quarrel
          over a point of honor [syn: {affaire d'honneur}]
     2: any struggle between two skillful opponents (individuals or
        groups)
     v : fight a duel, as over one's honor or a woman; "In the 19th
         century, men often dueled over small matters"
     [also: {duelling}, {duelled}]

duelling
     See {duel}