A self-contained unit which serves as a building block for the overall structure in space technology; usually designated by its primary function, such as command module or lunar landing module.

1. A distinct and identifiable unit of computer program for such purposes as compiling, loading, and linkage editing.

2. One memory bank and associated electronics in a computer.

A packaged assembly of wired components, built in a standardized size and having standardized plug- in or solderable terminations.

A unit of size used as a basic component for standardizing the design and construction of buildings, building parts, and furniture.

A vector space in which the scalars are a ring rather than a field.