(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.

(mathematics, physics, dynamical system theory) Given a (dynamical) system, any topological space such that every point in the space's underlying set uniquely represents a state of the system and every possible state is represented by some point;

(initially derogatory) A subgenre of speculative fiction or science fiction that emphasizes space travel, romantic adventure, and larger-than-life characters often set against vast exotic settings.

(neuroanatomy) The space between the arachnoid mater and the pia mater that surrounds the brain and spinal cord, through which the cerebrospinal fluid circulates and major blood vessels pass, and across which extend delicate trabeculae of connective tissue.

(transitive, intransitive) To format (a document) so that every other line is left blank, leaving sufficient whitespace for annotation (e.g. a teacher's corrections).

An opening made by the pupil in the eye.

(anatomy) The space in the wrist bounded by the hamate, capitate, triquetral and lunate bones.

(control engineering) A mathematical model of a physical system as a set of input, output and state variables related by first-order differential equations.

plural of space hopper

Alternative spelling of double-spaced