(mathematics) The real number system adjoined with two extra symbols: ∞ and −∞, inheriting the ordering of the real number system, and defining −∞ to be less than any real number, and ∞ to be larger than any real number.

(mathematics) A geometric representation of the real number system.

In mathematics, the extended real number system is obtained from the real number system by adding two elements denoted and that are respectively greater and lower than every real number.

(mathematics) The complete Archimedean ordered field (of real numbers).