stowaway
/ˈstoʊəweɪ/Definitions
1. noun
A person who secretly boards and travels on a ship or aircraft without paying or having a valid ticket.
“The ship’s crew discovered a stowaway in one of the cargo holds.”
2. verb
To travel secretly on a ship or aircraft, especially without paying or having a valid ticket.
“Some passengers tried to stowaway on the cruise ship to avoid paying for their tickets.”