(letterpress typography) A piece of metal type used to create the narrowest space. / (typography, US) The narrowest space appearing between letters and punctuation.

To type (or format) text without leaving a blank line between each line of text. / To type (or format) text with only one space between consecutive sentences.

A broad step between flights of a staircase. / (mathematics) Either of the two parts of three-dimensional space divided by a plane.

(mathematics) A Riemann space in which the contracted curvature tensor is proportional to the metric tensor

(astronomy) That part of outer space between the planets of a solar system and its star

(mathematics) Either of two spaces between which an isometry exists

(mathematics) Any metric space whose elements are functions

(of text) Formatted so that there is a full blank line between each line of text; the style of formatting required by many entities inside business, academia, and publishing.

simple past tense and past participle of double-space

(anatomy) Any of the spaces between the placental villi that contain maternal blood