an official document issued by the government of a country to one of its citizens and, varying from country to country, authorizing travel to foreign countries and authenticating the bearer's identity, citizenship, right to protection while abroad, and right to reenter his or her native country.

anything that ensures admission or acceptance

A good education can be your passport to success.

any authorization to pass or go somewhere.

a document issued to a ship, esp. to a neutral merchant ship in time of war, granting or requesting permission to proceed without molestation in certain waters.

a certificate intended to secure admission.

noun

authorization , credentials , key , license , pass , permit , safe-conduct , ticket , travel permit , visa , [[warrantnotes:a passport is an official government document issued by a country to a citizen allowing that person to travel abroad and re-enter the home country; a visa is an endorsement made in a passport that allows the bearer to enter the issuing country]] , conge , identification , safeguard , sea letter , voucher