mutual dependence; interdependence
A rare yojijukugo meaning that two parties are so closely connected that they cannot exist without each other, like lips and teeth or the cheek and jawbone. Used in formal or literary contexts.
The two countries are in a relationship of mutual dependence.
A similar yojijukugo also meaning mutual dependence, but 唇歯輔車 emphasizes the inseparability of the two parties more strongly.
The modern, neutral term for interdependence; 唇歯輔車 is a rare, literary expression.
From classical Chinese, combining the metaphors of lips and teeth (唇歯) and the cheek and jawbone (輔車) to express inseparable mutual dependence.