an undefeated champion一个未尝败绩的冠军

She was undefeated for 13 years.她13年来保持不败。

The two London clubs are the only undefeated teams in the division.伦敦那两家俱乐部是小组里仅有的不败球队。

Their undefeated season is still unmatched.他们赛季不败的纪录依旧无人能及。