From Classic Encyclopedia 1911
MANSION (through O. Fr. mansion, mod. maison, from Lat. mansio, dwelling-place, stage on a journey; manere, to remain), a term applied in early English use to the principal house of the lord of a manor. By the Settled Land Act 1890, § 10, subsec. 2, repealing § 15 of the act of 1882, "the principal mansion house ... on any settled land shall not be sold or exchanged or leased by the tenant for life without the consent of the trustees of the settlement or an order of the court." The principles guiding an English court of law for making or refusing such an order are laid down in In re the Marquess of Ailesbury's Settled Estate (1892), I Ch. 506, 546; A.C. 356. In general usage, the term "mansion" is given to any large and important house in town or country; and "mansion house" to the official residence, when provided, of the mayor of a borough, particularly to that of the lord mayors of London and Dublin. From the general meaning of a conspicuously large dwelling-place comes the modern employment of the term "mansions," in London and elsewhere, for large buildings composed of "flats."