a person who has defeated all opponents in a competition or series of competitions, so as to hold first place

the heavyweight boxing champion.

anything that takes first place in competition

the champion of a cattle show.

an animal that has won a certain number of points in officially recognized shows

This dog is a champion.

a person who fights for or defends any person or cause

a champion of the oppressed.

a fighter or warrior.

to act as champion of; defend; support

to champion a cause.

Obsolete . to defy.

first among all contestants or competitors.

Informal . first-rate.

adjective

poorest , worst

noun

loser

verb

be against , oppose

adjective

blue-ribbon , boss * , capital , chief , choice , cool , dandy , distinguished , first , greatest , head , illustrious , out of sight , out of this world , outstanding , premier , prime , principal , prize-winning , splendid , super , superior , tip top , top drawer , topflight , top-notch * , tops , unbeaten , undefeated , world class , ace , banner , brag , fine , first-class , first-rate , quality , superb , terrific , tiptop , top

noun

advocate , ally , backer , challenger , champ , conqueror , defender , endorser , exponent , expounder , guardian , hero , heroine , medalist , nonpareil , number one , numero uno , paladin , partisan , patron , proponent , protector , supporter , sympathizer , the greatest , titleholder , top dog , upholder , vanquisher , victor , vindicator , warrior , winner

verb

back , battle , contend , defend , espouse , fight for , go to bat for * , patronize , plead for , promote , put in a good word for , ride shotgun for , side with , stand behind , stand up for , support , thump for , uphold , advocate , endorse , get behind , plump for , recommend , stand by , ace , assert , backer , challenge , combatant , defender , fighter , firstrate , greatest , hero , heroine , maintain , medalist , outstanding , protect , squire , titleholder , unbeaten , undefeated , victor , vindicate , winner