1. A standardized, often interchangeable component of a system or construction that is designed for easy assembly or flexible use: a sofa consisting of two end modules.

2. Architecture A length used as a unit of measurement or as a standard for determining the proportions of a building.

3. Electronics A self-contained assembly of electronic components and circuitry, such as a stage in a computer, that is installed as a unit.

4. Computers A portion of a program that carries out a specific function and may be used alone or combined with other modules of the same program.

5. A self-contained unit of a spacecraft that performs a specific task or class of tasks in support of the major function of the craft.

6. A unit of education or instruction with a relatively low student-to-teacher ratio, in which a single topic or a small section of a broad topic is studied for a given period of time.

7. Mathematics An algebraic system that resembles a vector space, except that the set of scalars forms a ring and not necessarily a field.

8. Biology A unit of modular growth, such as a coral polyp.

9. Archaic A standard or unit of measurement.