败北 (bài běi) is a classical Chinese compound meaning 'to be defeated'—especially in military or competitive contexts. The character 败 (bài) means 'to lose' or 'to fail', while 北 (běi) originally meant 'north', but in ancient texts it also carried the sense of 'turning one’s back' (as in fleeing northward after defeat). Together, they form an elegant, formal term for suffering a decisive loss, often implying retreat or rout rather than mere failure.

This word is rarely used in casual speech; instead, it appears in historical narratives, news reports about major competitions or conflicts, literary writing, and formal speeches. It conveys gravity and finality—more solemn than common synonyms like 输 (shū) or 失败 (shībài). While not limited to warfare, its roots lie in ancient battlefield terminology, and modern usage still evokes that tone of dignified, consequential loss.