What is the term used for a smaller component of a larger system?

The term used for a smaller component of a larger system is "subsystem." A subsystem is essentially a smaller, self-contained system that functions as a part of a larger system. It has its own distinct functions and components, but it also interacts with other subsystems to contribute to the overall operation of the larger system. This concept is widely applicable across various fields, such as engineering, biology, and organizational structure, where complex systems are often composed of multiple interconnected subsystems that work together to achieve a common goal.

The other terms presented, like microsystem, component, and module, may refer to smaller parts or specific aspects of systems but do not convey the same idea of being an integral part of a larger system with its own distinct functionalities. For instance, a component may refer to any part of a system without the implication of it working independently and collaboratively as a subsystem.