Module

noun

1. A self-contained component of a system, often interchangeable, which has a well-defined interface to the other components.
2. A standard unit of measure used for determining the proportions of a building.
3. A section of a program; a subroutine or group of subroutines.
4. A unit of education covering a single topic.

   "Which modules are you studying next year?"

5. A pre-prepared adventure scenario with related materials for a role-playing game.