0 someone who tries to win a competition, fight, or sports event from someone who has previously won it --
1 someone who tries to win a competition and achieve a position, esp. in politics or sports, against someone who has won it and now has that position: --
An aide to Buchanan said the conservative challenger for the presidency would hold a press conference tomorrow.
First, challengers against safe incumbents tend to be inexperienced and thus spend money inefficiently.
Electorally speaking, there were no credible challengers as a consequence of weak party competition.
The greatest possible offer the challenger can make is to spend all available resources optimally on the smallest possible coalition.
Finally, the authors argue that grammar-based language models are serious challengers for corpus-based models.
She can credibly commit to include these individuals in every future coalition, while the challenger can offer them access to future private goods only probabilistically.
What remains unanswered, and mostly unaddressed, is an explanation of when challengers succeed in upsetting an industry and the standards imposed by dominant firms.
Apparently challengers who are disadvantaged in terms of resources and name recognition offer moderate positions in an attempt to compensate for their non-policy liabilities.
According to him, incumbent politicians in democracies have to fear that challengers mobilise disaffected voters.
