Champion is a word that originally comes from Old French "champiun", meaning "combatant, fighter".
In modern usage, champion primarily refers to:
1. A person who has defeated all opponents in a competition, series of competitions, or in a particular field
2. Someone who vigorously supports or defends a person or cause
3. In informal contexts, something that is excellent or outstanding
4. As a verb, to support or defend a cause or person