plugin

This term describes a modular addition to software, evoking the image of a physical electrical plug being inserted into a socket to provide immediate power or functionality. It carries a connotation of convenience and extensibility, suggesting that the primary application is a chassis that can be customized by the user based on their specific needs.

In technical discourse, it is often used interchangeably with add-on or extension, though plugin specifically implies a standardized interface that allows third-party developers to integrate their code into a host application. It is a neutral, technical term used across all levels of formality in computing.