When referring to smaller parts or components of a bigger structure, the term sub-units is often used. However, there are numerous synonyms that can be used in place of this term depending on the context in which it is being applied. Some of these synonyms include sub-components, sub-entities, substructures, sub-elements, sub-parts, and sub-modules. Each of these terms describes a smaller, self-contained unit that makes up a larger system. Depending on the field or industry, different synonyms may be more appropriate. Nonetheless, they all indicate a section of something bigger, and they can be used interchangeably with sub-units to create more diversity in writing and to avoid repetition.