Real Dictionary

passport
countable noun: If you say that a thing is a passport to success or happiness, you mean that this thing makes success or happiness possible.
countable noun: Your passport is an official document containing your name, photograph, and personal details, which you need to show when you enter or leave a country.

passport in American English
a government document issued to a citizen for travel abroad, subject to visa requirements, certifying identity and citizenship: it entitles the bearer to the protection of his or her own country and that of the countries visited
noun: 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 ri

passport in British English
noun: an official document issued by a government, identifying an individual, granting permission to travel abroad, and requesting the protection of other governments for him or her
verb: (in the European Economic Area) to award a firm that is registered in one member state the right to do business in every other member state without applying to each country for authorization