1.Open or free admission to all; hospitable welcome; free opportunity. "She of the open soul and open door, With room about her hearth for all mankind."
2.In modern diplomacy, opportunity for political and commercial intercourse open to all upon equal terms, esp. with reference to a nation whose policy is wholly or partially fixed by nations foreign to itself, or to territory newly acquired by a conquering nation. In this sense, often used adjectively, as, open-door system, open-door policy, etc. "The steps taken by Britain to maintain the open door have so far proved to be perfectly futile."
...
