passport

noun

1. 1

   An official document normally used for international journeys, which proves the identity and nationality of the person for whom it was issued.

   “You will have to bring your passport to prove who you are.”

2. 2

   (by extension) Any document that allows entry or passage.

3. 3

   Something which enables someone to do or achieve something.

   “The tenor's voice was his passport to the international concert circuit.”