antechamber

2. A small outer room that leads into a main hall or chamber.

The antechamber was crowded with visitors hoping for an audience with the king.

3. A room used as a waiting area before entering a formal space.

She sat quietly in the antechamber until her name was called.

4. A small room attached to a larger one, often used for private meetings.

The two leaders spoke briefly in the antechamber before the public ceremony.