Passport

Permission to pass; a document given by the competent officer of a state, permitting the person therein named to pass or travel from place to place, without molestation, by land or by water.

A document carried by neutral merchant vessels in time of war, to certify their nationality and protect them from belligerents; a sea letter.

A license granted in time of war for the removal of persons and effects from a hostile country; a safe-conduct.

Figuratively: Anything which secures advancement and general acceptance.

any quality or characteristic that gains a person a favorable reception or acceptance or admission; "her pleasant personality is already a recommendation"; "his wealth was not a passport into the exclusive circles of society"

a document issued by a country to a citizen allowing that person to travel abroad and re-enter the home country