stowaway

A person who hides aboard a ship or other conveyance in order to obtain free passage.

One who, in order to secure a free passage, conceals himself aboard an outward-bound vessel, with the hope of remaining undiscovered until too late to be sent ashore.

One who conceals himself board of a vessel about to leave port, or on a railway train, in order to obtain a free passage.

a person who hides on board a ship, train, etc. so as to get a free passage

hide aboard a ship or a plane to get free transportation

a person who hides aboard a ship or plane in the hope of getting free passage