Gun-running refers to the illegal transportation of firearms across international borders. It is a serious crime that is often associated with organized crime and terrorism. However, there are many different terms that can be used to describe this activity, each with slightly different nuances. Some of the most common synonyms for gun-running include weapons trafficking, arms smuggling, and illicit arms trade. Other related terms include gun smuggling, illegal arms sales, and gray market firearms. These terms are often used interchangeably, but they all refer to the same basic activity of moving firearms across borders without proper authorization or oversight. Regardless of the specific terminology used, gun-running is a dangerous and illegal activity that poses a serious threat to public safety and security.