'Challenger' definitions:

Definition of 'challenger'

(from WordNet)
noun
The contestant you hope to defeat; "he had respect for his rivals"; "he wanted to know what the competition was doing" [syn: rival, challenger, competitor, competition, contender]

Definition of 'Challenger'

From: GCIDE
  • Challenger \Chal"len*ger\, n. One who challenges. [1913 Webster]