According to a quick google search:
- A hinged, sliding, or revolving barrier at the entrance to a building, room, or vehicle, or in the framework of a cupboard.
- A hinged barrier used to close an opening in a wall, fence, or hedge.
It doesn't specify internal or external. An opening in a wall could be internal or external.
And just a couple of Merriam-Webster links:
Retired English Teacher