n. Dominion; province of action; range or extent of authority: as, to trench on one's domain by interference.n. The territory over which dominion is exercised; the territory ruled over by a sovereign, or under the government of a commonwealth: as, the domains of Great Britain.n. An estate in land; landed property.n. The land about the mansion-house of a lord, and in his immediate occupancy.n. In law, ownership of land; immediate or absolute ownership; permanent or ultimate ownership. In the last two senses the word coincides with demain, demesne.n. The range or limits of any department of knowledge or sphere of action, or the scope of any particular subject: as, the domain of religion, science, art, letters, agriculture, commerce, etc.; the judicial domain.n. In logic, the breadth, extension, circuit, or sphere of a notion.n. In the United States, the lands owned by the federal government or by a State; the public lands held for sale or reserved for specific uses.n. In mathematics: A set of numbers when the sums, differences, products, and quotients of any numbers in the set (excluding only the quotients of division by 0) always yield as results numbers belonging to the set.n. The space within which a given function is developable in a series in powers of z–a: termed the domain of the point, z = adjectiven. In function-theory, the region of the z-plane within a circle about a as center with any radius less than the distance from a to the nearest critical point: called the domain of its center a.