The Collaborative International Dictionary of English v.0.48:

Conqueror \Con"quer*or\ (k[o^][ng]"k[~e]r*[~e]r), n. [OF.
   conquereor, fr. conquerre,]
   One who conquers.
   [1913 Webster]

   The Conqueror (Eng. Hist.). William the Norman (1027-1067)
      who invaded England, defeated Harold in the battle of
      Hastings, and was crowned king, in 1066.
      [1913 Webster]

WordNet (r) 3.0 (2006):

conqueror
    n 1: someone who is victorious by force of arms [syn:
         conqueror, vanquisher]

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "conqueror":
   champ, champion, conquering hero, conquistador, defeater,
   easy winner, hero, master, pancratiast, runner-up, shoo-in,
   subduer, subjugator, sure winner, top dog, triumpher, vanquisher,
   victor, winner