the contestant you hope to defeat
"he had respect for his rivals"
"he wanted to know what the competition was doing"
One who challenges; especially, one who plays against the current champion of a game or contest in hopes of winning and becoming the new champion.
"The New York Central M1 Challenger was a massive steam locomotive featuring the distinctive 4-6-6-4 wheel arrangement."
a steam locomotive of the 4-6-6-4 wheel arrangement.
In plain English: A challenger is someone who tries to defeat an established leader or take over their position.
"The challenger launched her campaign for mayor against the incumbent leader."
Usage: Use "challenger" to refer specifically to an opponent seeking to defeat a reigning titleholder, rather than using it as a general synonym for anyone who contests something. Avoid confusing this noun with the verb form when describing the act of issuing a challenge itself.
A space shuttle, named after HMS Challenger (1858), destroyed on January 28, 1986 with loss of its seven-member crew.
"The Challenger disaster shocked the nation when the ill-fated space shuttle broke apart just minutes after liftoff."
The word challenger comes from the Middle English chalenger, which originally described someone who made false accusations or issued disputes. Over time, its meaning shifted in English to refer specifically to a person who issues a formal challenge.