ˌopen-ˈdoor ˌpolicy noun [countable]

1. the principle of allowing people and goods to move into a country freely:
They’re pushing forward economic reform and an open-door policy.

2. the principle of allowing anyone to come to a place at any time, for example in order to discuss something

[TahlilGaran] Dictionary of Contemporary English ▲

open door policy
n. phr. A policy that states that newcomers are welcome to join the company, firm, or country in question.
During the nineteenth century the United States had an open-door policy regarding immigration.

[TahlilGaran] English Idioms Dictionary ▲