Other forms: champions, championed, championing
A champion is the person or team that has beaten everybody else. World champion, the reigning champion, champion of the league.
There is a second and older sense that is entirely different: a champion of something is somebody who fights for a cause — a champion of free speech, champion the rights of. The verb comes from that: to champion an idea is to argue publicly for it. Note the northern English use of champion as an adjective meaning excellent — that's champion — which is regional and warm, and champion in dog and livestock showing, which is a formal title.
1nounchampionThe winner of a competition.
“They were champions three seasons running.”
2nounpubliclySomebody who publicly supports a cause.
“She was a champion of the campaign from the start.”
3verbsupportTo support a cause publicly.
“He championed the scheme when nobody else would.”
Too few real examples of this word to estimate which sense is commonest.
champion is a winner, or a supporter.
Medieval Latin campio meant a fighter in a duel, from Latin campus, a field — the field of combat. A champion was originally somebody who fought a judicial duel on another person's behalf, which is exactly what championing a cause still means.
Proto-Indo-European
*kh₂em-
Middle English
champioun
English, today
champion
Built from
From Middle English champioun. From Middle English champioun, from Old French champion, from Medieval Latin campio (“combatant in a duel, champion”), from Frankish kampijō (“fighter”), from Proto-West Germanic kampijō (“combat soldier”), a derivative of kampijan (“to battle, to campaign”), itself a derivative of kamp (“battlefield, battle”), ultimately a borrowing in West-Germanic from Latin campus (“a field, a plain, a place of action”). Cognate with Old English cempa, cempa (“soldier, warrior, champion”), Old High German kempfo, kempfo (“fighter, warrior, champion”), whence archaic German Kempfe (“fighter”).
Etymology from Wiktionary, CC BY-SA