Gate

1. A structure that can be swung, drawn, or lowered to block an entrance or a passageway. Our house has a gate on the driveway to halt unwanted visitors.
2. An opening is a wall or fence for entrance or exit. Close the gate after you pass through.
3. A means of access. Education can be a gate to riches.
4. A passageway, as in an airport terminal, through which passengers proceed fro embarkation. You must go through a security gate before boarding your plane.