maritime law. A paper containing a permission from the neutral state to the captain or master of a ship or vessel to proceed on the voyage proposed; it usually contains his name and residence; the name, property, description, tonnage and destination of the ship; the nature and quantity of the cargo; the place from whence it comes, and its destination; with such other matters as the practice of the place requires. 2. This document is indispensably necessary in time of war for the safety of every neutral vessel. . 3. In most countries of continental Europe passports are given to travelers; these are intended to protect them on their journey from all molestation, while they are obedient to the laws. Passports are also granted by the secretary of state to persons travelling abroad, certifying that they are citizens of the United States.