champion

Concise Oxford English Dictionary © 2008 Oxford University Press:
champion/ˈtʃampiən/

▶noun

• 1 a person who has surpassed all rivals in a sporting contest or other competition.

• 2 a defender of a cause or person.

  ■ historical a knight who fought in single combat on behalf of the monarch.

▶verb support the cause of. ▶adjective Brit. informal or dialect excellent.

– origin ME: from OFr., from med. L. campio(n-) ‘fighter’, from L. campus (see camp1).