What is Concourse?

Legal Definition
A concourse is a place where pathways or roads meet, such as in a hotel, a convention centre, a railway station, an airport terminal, a hall, or other space.

The term is not limited to places where there are literally pathways or roadways or train tracks joining. An alternate meaning now is "an open space or hall (as in a railway terminal) where crowds gather." In this meaning as a place where crowds gather, while many persons in any crowd no doubt have followed different paths in their lives to get to the place, there need not be notable specific roadways leading to the place.
-- Wikipedia
Legal Definition
A terminal area where the plane is connected to the building.