Chinese idiom · 成语
唇齿相依
Meaning
Lips and teeth rely on each other; close interdependence.
Character by character
Origin and story
Literary expressionSanguo Zhi (三國志), volume 12, records Bao Xun explaining why repeated Wei campaigns have not overcome Wu and Shu. The two rival states support one another like lips and teeth, he argues, and their mountains and waterways strengthen their position. The expression describes a strategic relationship that makes each harder to defeat.
The same image appears in Jin Shu in a discussion of the imperial clan and relatives by marriage providing mutual support. Later usage extends well beyond states and court politics. It describes closely connected parties whose security or success depends on one another, rather than friendship based only on affection.
Sources and further reading
In everyday life
这家面包店和隔壁咖啡馆唇齿相依，常常互相介绍客人。
The bakery and the café next door depend on each other and often send customers each other’s way.
Emphasizes mutual dependence, not simply being physically close.