a person, team, etc. that has won a competition, especially in a sport; the world basketball champions; a champion jockey/boxer/swimmer, etc.

​champion something to fight for or speak in support of a group of people or a belief. He has always championed the cause of gay rights.

to fight for or speak in support of a group of people or a belief. He has always championed the cause of gay rights.

There are four meanings listed in OED's entry for the verb champion, one of which is labelled obsolete. See 'Meaning & use' for definitions, usage, and ...

a competition to find the best player or team in a particular sport. Extra Examples She's won the championship for the third time in a row.

someone or something, especially a person or animal, that has beaten all other competitors in a competition: an Olympic champion.

the jockey who has won the most horse races in a season. There are two champion jockeys each year, the one who wins the most steeplechases.

a competition to find the best player or team in a particular sport; the National Basketball Association Championship.

​an informal way of referring to a champion, often used in newspapers. Scottish champs celebrate victory! The former heavyweight boxing champ has finally ...