Stowaways are individuals who secretly board a vehicle or vessel without authorization. There are several synonyms for stowaways that can be used to describe people who engage in this behavior. Some alternative words include smugglers, interlopers, trespassers, stow-ins, freeloaders, hitchhikers, and clandestine passengers. While all of these terms can refer to individuals who sneak on board, they may also carry additional nuances. For example, smugglers might be transporting prohibited goods, while hitchhikers may simply be looking for a ride. Regardless of the word used, stowaways are generally viewed as a security risk and can incur legal consequences if discovered.