Plug-in and Printed circuit

Plug-in noun - A printed circuit that can be inserted into expansion slots in a computer to increase the computer's capabilities.

Printed circuit and plug-in are semantically related. In some cases you can use "Printed circuit" instead a noun phrase "Plug-in".

Printed circuit noun - Computer circuit consisting of an electronic sub-assembly; copper conductors are laminated on an insulating board or card and circuit components are inserted into holes and dip soldered.

Plug-in and printed circuit are semantically related. Sometimes you can replace phrase "Plug-in" with "Printed circuit", this phrases are similar.