Wiktionary
great room
n. In many modern homes, the room that replaces the living room.
Wikipedia
Great room
A great room is a room space within an abode which combines the specific functions of several of the more traditional room spaces (e.g. the family room, the living room, the study, etc.) into a singular unified space. Great rooms are typically at or near the center of the house, feature raised ceilings, and have been common in American homes since the early 1990s.
The New York Times called the great room "the McMansion's signature space."
Usage examples of "great room".
She sailed like a fullrigged vessel across the great room, took the gloves from the drawer, and with the boys beside her, watched the President, sternly, while he worked his great hands into the white kids.