champion

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One that wins first place or first prize in a competition.
• noun One that is clearly superior or has the attributes of a winner.
• noun An ardent defender or supporter of a cause or another person.
• noun One who fights; a warrior.
• transitive verb To fight for, defend, or support as a champion: synonym: support.
• transitive verb Obsolete To defy or challenge.
• adjective Holding first place or prize.
• adjective Superior to all others.

from The Century Dictionary.

• See champian.
• noun One who undertakes to defend any cause; especially, one who engages in combat or contention in behalf of another, or in any representative capacity: as, the champion of an army or of a party; a champion for the truth, or of innocence.
• noun More generally, a hero; a brave warrior.
• noun One who has demonstrated his superiority to all others in some matter decided by public, contest or competition, as prize-fighting, pedestrianism, rowing, plowing, etc.
• First among all competitors or contestants: as, a champion oarsman.
• Hence By extension, of the first rank or highest excellence in any respect; unexcelled.
• noun An animal or a plant to which, or to its owner, the first prize has been awarded in any general competition, as at a horse-, cattle-, bench-, or other show, or which has taken a number of prizes.
• noun Some variety of vegetable, fruit, implement, or the like, for which the highest excellence is claimed.
• To maintain or support by contest or advocacy; act as champion for.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who engages in any contest; especially one who in ancient times contended in single combat in behalf of another's honor or rights; or one who now acts or speaks in behalf of a person or a cause; a defender; an advocate; a hero.
• noun One who by defeating all rivals, has obtained an acknowledged supremacy in any branch of athletics or game of skill, and is ready to contend with any rival.
• transitive verb To furnish with a champion; to attend or defend as champion; to support or maintain; to protect.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Someone who has been a winner in a contest.
• noun Someone who is chosen to represent a group of people in a contest.
• adjective attributive Acting as a champion; that has defeated all one's competitors.
• adjective attributive Excellent; beyond compare.
• adjective (Ireland, colloquial) Excellent; superb; deserving of high praise.
• verb to promote, advocate, or act as a champion for

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun someone who has won first place in a competition
• noun someone who is dazzlingly skilled in any field
• noun someone who fights for a cause
• verb protect or fight for as a champion
• noun a person who backs a politician or a team etc.
• adjective holding first place in a contest