mansion house (UK)—
1. the house of a landed proprietor:
- The landed gentry usually possess a share of pride fully proportionate to their estate and mansion house.
2. (the Mansion House) the official residence of the Lord Mayor of London:
- The conference took place in the Egyptian Hall of the Mansion House, the Lord Mayor presiding.
mansion house (U.S.)—a large house of good appearance:
- In this street were most of the great houses, or “mansionhouses,” as it was usual to call them.