module -
a self-contained component (unit or item) that is used in combination with other components
component,
constituent,
element an artifact that is one of the individual parts of which a composite entity is made up; especially a part that can be separated from or attached to a system; "spare components for cars"; "a component or constituent element of a system"
system instrumentality that combines interrelated interacting artifacts designed to work as a coherent entity; "he bought a new stereo system"; "the system consists of a motor and a small computer"
cartridge ammunition consisting of a cylindrical casing containing an explosive charge and a bullet; fired from a rifle or handgun
module -
computer circuit consisting of an assembly of electronic components (as of computer hardware)