A factor can be:

1. a person acting as a mercantile agent
2. a number that is a divisor of another number in mathematics;
3. an enzyme in biochemistry.
4. an abbreviation for Functionality, Application domain, Conditions, Technology, Objects, and Responsibility in the OOA&D method.
5. a leader of a cell in one of the philosophical factions in the Planescape setting for Dungeons & Dragons.
6. a von Neumann algebra with a trivial center.
7. the Factor programming language, created by Slava Pestov