airspace

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The portion of the atmosphere directly above the land or water, used by aircraft or by earth-based structures such as skyscrapers.
• noun The airspace of a particular jurisdiction, such as a nation.

from The Century Dictionary.

• noun In ornithology, an air-cell of large size; an air-receptacle or a pneumatocyst (which see).
• noun In medicine and sanitary science, the clear cubic contents of a room, as the ward of a hospital, with reference to the respirable air contained in it: as, air-space per man, so many cubic feet.
• noun In firearms, a vacant space between the powder-charge and the projectile.

from the GNU version of the Collaborative International Dictionary of English.

• noun the atmosphere above a nation and deemed to be under its jurisdiction.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun politics, aviation A specified portion of the atmosphere, especially that under the technical aviation control and/or jurisdiction of a particular state over which territory (and territorial waters) it lies.
• noun aviation A designated part of the sky for aircraft use.
• noun broadcasting Space (i.e. a few neighboring frequencies) available for broadcasting within a particular frequency band.
• noun The portion of an enclosed area which contains air, especially breathable air.
• noun construction The cavity in a cavity wall containing air for insulation.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the space in the atmosphere immediately above the earth
• noun the atmosphere above a nation that is deemed to be under its jurisdiction
• noun the space in the atmosphere immediately above the earth