The Collaborative International Dictionary of English v.0.48:

Championship \Cham"pi*on*ship\, n.
   State of being champion; leadership; supremacy.
   [1913 Webster]

WordNet (r) 3.0 (2006):

championship
    n 1: the status of being a champion; "he held the title for two
         years" [syn: championship, title]
    2: a competition at which a champion is chosen
    3: the act of providing approval and support; "his vigorous
       backing of the conservatives got him in trouble with
       progressives" [syn: backing, backup, championship,
       patronage]

Moby Thesaurus II by Grady Ward, 1.0:

86 Moby Thesaurus words for "championship":
   Cadmean victory, KO, Pyrrhic victory, abetment, acme, advocacy,
   aegis, ascendancy, auspices, authority, authorization, backing,
   be-all and end-all, blue ribbon, care, charity, command, conquest,
   control, countenance, directorship, dominion, easy victory,
   effectiveness, encouragement, favor, first place, first prize,
   fosterage, goodwill, grand slam, guidance, headship, hegemony,
   height, highest, imperium, influence, interest, jurisdiction,
   kingship, knockout, landslide, landslide victory, leadership,
   lordship, management, mastership, mastery, maximum, moral victory,
   most, ne plus ultra, new high, palms, paramountcy, patronage,
   picnic, power, presidency, primacy, pushover, record, rule,
   runaway victory, say, seconding, sovereignty, sponsorship, subdual,
   subduing, success, supremacy, sway, sympathy, top spot,
   total victory, triumph, tutelage, victory, walkaway, walkover, win,
   winning, winning streak, zenith