The term "royal prince" typically refers to a male member of a royal family. There are many different synonyms that can be used to describe this role, depending on the specific culture or historical context. Some possible alternatives include "crown prince," which refers to the designated heir or successor to the throne; "heir apparent," which indicates that the prince is expected to become the next ruler; "prince regent," which refers to someone who rules on behalf of a monarch who is unable to govern; and "princeling," which can have a somewhat negative connotation and may imply that the prince has limited power or authority. Ultimately, the right synonym depends on the specific circumstances and tone of a given text or conversation.