1. A dwelling place, whether a part or whole of a house or other shelter. In my fathers house are many mansions. (john xiv. 2) These poets near our princes sleep, And in one grave their mansions keep. (Denam)
4. The place in the heavens occupied each day by the moon in its monthly revolution. The eight and twenty mansions That longen to the moon. (Chaucer) mansion house, the house in which one resides; specifically, in london and some other cities, the official residence of the lord Mayor.