(topology, formally) An ordered pair (X, τ), where X is a set and τ, called the topology, is a collection of subsets of X which satisfies certain axioms and whose elements are called the open sets (or alternatively, for a different set of axioms, the closed sets);

(mathematics) A subset of Euclidean space in which tensors are used to describe distance, angle, and curvature

A narrow opening underneath the bottom of a building (or storey) used to give access to pipes, cables and other utilities

Any activity performed by an astronaut outside of a space vehicle in space.

(physics) The quantization of one or more components of the angular momentum of a system

(mathematics) A vector space whose basis of real numbers has three vectors

(uncountable) The application of science and engineering to the exploration and utilization of outer space / (countable) Any particular scientific or engineering discipline used in this field

(uncountable) Flight into, from or through space. / (countable) A voyage in space.

Alternative spelling of double-spaced

(functional analysis) A normed vector space which is complete with respect to the norm, meaning that Cauchy sequences have well-defined limits that are points in the space.