challenger

One who challenges.

[C]ertainly there is no true orator who is not a hero. […] He is challenger and must answer all comers.

Debates are often unpredictable, but it is especially hard to game out how this debate featuring a moderate standard-bearer and a liberal challenger will unfold and how people will process it. Hundreds of thousands of viewers, if not millions, will have been personally affected by Sunday, as public gathering spaces are shuttered, schools are closed and on Thursday the stock market plunged by the largest percentage in decades (it snapped back upward on Friday).

One who challenges.

challengers of traditional attitudes

One who challenges.

The champion hopes to defeat his new challenger in the game to remain undefeated.

One child stood as king of the hill, and tried to withstand the pushes and shoves of his challengers.

One who challenges.

Novv vvhen they vvere come before Appius, ſitting judicially upon his tribunall ſeate, the plaintife or challenger aforeſaid, declareth againſt her, […]

Often in the form Challenger: a match, tournament, or tour of the second-highest tier organized by the Association of Tennis Professionals.

A space shuttle, named after HMS Challenger (1858), destroyed on January 28, 1986 with loss of its seven-member crew.

A steam locomotive of the 4-6-6-4 wheel arrangement.

American Locomotive Company, which introduced the 4-6-6-4 (on Union Pacific) in 1936, constructed more Challengers than any other builder and, in Northern Pacific's Z-8 class, built the heaviest. NP owned 48 4-6-6-4's in three classes.

Alternative letter-case form of challenger (“a match, tournament, or tour of the second-highest tier organized by the Association of Tennis Professionals”).