There are many synonyms for the term "regular customer" that can be used interchangeably depending on the context. Some common synonyms include "loyal customer," "repeat customer," "frequent customer," and "returning customer." These terms all refer to individuals who regularly patronize a business and are valued for their consistent patronage. Other synonyms for regular customers might include "dedicated customers," "established clients," and "core customers." In short, any term that emphasizes the reliability and consistency of a customer's business with a company may be considered a synonym for "regular customer".