Ingredient and Plug-in

Ingredient noun - One of the parts that make up a whole.

Plug-in and ingredient are semantically related In some cases you can use "Plug-in" instead a noun "Ingredient".

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

Ingredient and plug-in are semantically related in part topic. You can use "Ingredient" instead a noun phrase "Plug-in", if it concerns topics such as element.