"allowing and gauging of intervals between words in setting type," 1680s, verbal noun from space (v.).
1540s, "to make of a certain extent;" 1680s in typography; 1703 as "to arrange at set intervals," from space (n.). Meaning "to be in a state of drug-induced euphoria" is recorded from 1968. Space cadet "eccentric person disconnected with reality" (often implying an intimacy with hallucinogenic drugs) is a 1960s phrase, probably traceable to 1950s U.S. sci-fi television program "Tom Corbett, Space Cadet," which was watched by many children who dreamed of growing up to be one and succeeded. Related: Spaced; spacing.