outer space. 1. The known and unknown areas of the universe beyond airspace. • The boundary between airspace and outer space is not fixed or precise. Cf. AIRSPACE. 2.Int’l law. The space surrounding the planet that by United Nations treaty is not subject to claim of appropriation by any national sovereignty. • The treaty does not expressly define outer space. See OUTER SPACE TREATY .

[Blacks Law 8th]