ˈpləg-ˌinHow to pronounce plug-in (audio)

: designed to be connected to an electric circuit by plugging in a plug-in toy a plug-in circuit board

1 : something that plugs in

2 : a small piece of software that supplements a larger program (such as a browser)

intransitive verb

: to establish an electric circuit by inserting a plug

transitive verb

: to attach or connect to an electric receptacle (such as an outlet)