Quick definitions from WordNet (champion)

▸ noun:  someone who fights for a cause
▸ noun:  someone who has won first place in a competition
▸ noun:  someone who is dazzlingly skilled in any field
▸ noun:  a person who backs a politician or a team etc.
▸ verb:  protect or fight for as a champion
▸ adjective:  holding first place in a contest ("A champion show dog")
▸ name:  A surname (common: 1 in 14285 families; popularity rank in the U.S.: #1899)

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▸ Also see champion