1. plug-in - Noun
2. plug-in - Adjective
3. plug-in - Verb
a printed circuit that can be inserted into expansion slots in a computer to increase the computer's capabilities
a software module that extends or enhances the capabilities of an existing application
plug into an outlet
Source: WordNetplug in
The Adobe flash plug-in is non-free software, and people should not install it, or suggest installing it, or even tell people it exists. Richard Stallman
Perhaps the most versatile and useful plug-in in the collection is Mass Copy. It is certainly the one I use the most. Due to limitations in how plugins can interact with Finale, Mass Copy has a somewhat unusual user interface. Robert Patterson
The general reactions were that the video was either not going to load, or be painfully slow to load, or would require a plug-in users didn't have. YouTube changed that, because it just works. Steve Krug
Please plug in the toaster! Source: Internet
Connect the TV so we can watch the football game tonight Source: Internet
A backplane uses plug-in cards for storage and processing. Source: Internet