Relatively prime is a term in number theory that describes two integers that do not share any common factors except 1. There are several synonyms for the term relatively prime, including coprime, mutually prime, and prime to each other. Coprime is a commonly used synonym for relatively prime, particularly in British English. Mutually prime is another synonym that is less commonly used but means the same thing. Prime to each other means that both numbers are prime and have no common factors, but it is less commonly used than coprime or relatively prime. Regardless of the word used, all of these synonyms describe the same mathematical concept.