undefeated
adjective /ˌʌndɪˈfiːtɪd/
  /ˌʌndɪˈfiːtɪd/
- (especially in sport) not having lost or been defeated
- They are undefeated in 13 games.
 - the undefeated world champion
 
Oxford Collocations DictionaryUndefeated is used with these nouns:- champion
 - season
 - streak
 - …