Origin: 1175–1225; Middle English < Old French < Late Latin campiōn- (stem of campiō) < West Germanic *kampiōn-, equivalent to kamp- battle (< Latin campus field, battlefield) + -iōn- noun suffix; compare Old English cempa warrior, etc.
early 13c., from O.Fr. champion, from L.L. campionem (nom. campio) "gladiator, combatant in the field," from L. campus "field (of combat);" see campus. Had been borrowed earlier by O.E. as cempa. The verb "to fight for, defend, protect" is from 1820.