The FAL Convention defines a stowaway as "A person who is secreted on a ship, or in cargo which is subsequently loaded on the ship, without the consent of the shipowner or the Master or any other responsible person and who is detected on board the ship after it has departed from a port, or in the cargo while unloading it in the port of arrival, and is reported as a stowaway by the master to the appropriate authorities".

To summarize, a stowaway is someone who hides him or herself on a ship, or in cargo, without the permission or knowledge of the shipowner, ship’s Master or crew, and who is onboard the vessel once it has left port.

According to the convention for Facilitation of International Maritime Traffic, a stowaway on a ship is someone who boards the vessel without the consent of the shipowner, the master or any other responsible person and is found after the ship has left the port of call or during the unloading process at the port of arrival.