concourse
A large open indoor area where many people walk or wait.
A concourse is a large, open area inside a building where many people can gather, walk through, or wait. You'll find concourses in airports, train stations, and shopping malls: wide spaces designed for crowds to move around without getting jammed up.
Picture the main hall of a busy airport, with travelers pulling suitcases, checking departure boards, and heading toward their gates. That's a concourse. It's much bigger than a hallway and serves as a central meeting point where multiple paths come together. Grand Central Terminal in New York has a famous concourse with a beautiful painted ceiling, where thousands of people cross paths every day.
Modern concourses often have shops, restaurants, and information desks because so many people pass through them. When you hear that there's construction on the upper concourse of a stadium, it means work is happening in those wide walking areas where fans gather before heading to their seats.