( plug-ins)
1.
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.
...a plug-in radio.
ADJ : ADJ n
2.
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. ( COMPUTING )
...a plug-in memory card.
N-COUNT : oft N n