1. 插入式的；带插头接点的
A plug-in machine is a piece of electrical equipment that is operated by being connected to an electricity supply or to another piece of electrical equipment by means of a plug.
2. 插件；插件程序
A plug-in is something such as a piece of software that can be added to a computer system to give extra features or functions.
1. a printed circuit that can be inserted into expansion slots in a computer to increase the computer's capabilities