‘接口’ (jiē kǒu) literally means ‘join mouth’ — ‘接’ (jiē) means ‘to connect, join, or receive’, and ‘口’ (kǒu) means ‘mouth’ or ‘opening’. Together, they metaphorically refer to a point of interaction or connection between two systems, devices, or components. In modern usage, it most commonly denotes a technical interface — such as a hardware port (e.g., USB interface), a software API (application programming interface), or a standardized communication channel.

The term is widely used in computing, electronics, engineering, and even in abstract contexts like human-computer interaction or organizational coordination. While originally rooted in physical connection points, ‘接口’ now extends to logical and procedural boundaries where data, functions, or responsibilities are exchanged. It carries a neutral, formal register and appears frequently in technical documentation, product specifications, and IT discussions.