Merriam-Webster Collegiate Dictionary - champion

 I. noun  Etymology: Middle English, from Anglo-French, from Medieval Latin campion-, campio, of West Germanic origin; akin to Old English cempa warrior  Date: 13th century  1. warrior, fighter  2. a militant advocate or defender a ~ of civil rights  3. one that does battle for another's rights or honor God will raise me up a ~ — Sir Walter Scott  4. a winner of first prize or first place in competition; also one who shows marked superiority a ~ at selling  II. transitive verb  Date: 1605  1. archaic challenge, defy  2. to protect or fight for as a ~  3. to act as militant supporter of ; uphold, advocate always ~s the cause of the underdog  Synonyms: see support