When discussing industrial hubs, the term "factory districts" is commonly used. However, there are several synonyms that can be used in place of this term. One alternative is "industrial precincts", which refers to designated areas within a city or town where industrial activity is concentrated. "Manufacturing zones" is another synonym that can be used to refer to areas where manufacturing takes place. Other options include "industrial parks", "production centers", and "factory zones". Each of these synonyms accurately captures the concept of a designated area where industrial activity is centered, and can be used interchangeably with the term "factory districts".