The Collaborative International Dictionary of English v.0.48:
Challenger \Chal"len*ger\, n. One who challenges. [1913 Webster]WordNet (r) 3.0 (2006):
challenger n 1: 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]