noun which may take the genitive case particle 'no', noun
undefeated; unbeaten
Describes a person, team, or record that has never lost. Often used in sports and competitive contexts.
そのボクサーは無敗のまま引退した。
The boxer retired undefeated.
我が校のサッカー部は今シーズン無敗だ。
Our school's soccer team is undefeated this season.