airspace

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The portion of the atmosphere above a particular land area, especially that of a political subdivision such as a nation.
2. n. The space occupied by an aircraft.
3. n. A designated sector of space, such as that in the vicinity of an airport.
4. n. Chiefly British Space available for broadcasting within a particular frequency: "Mobile radio has to compete for air space with other services such as broadcast radio, television, and even military services” ( Financial Times).
5. n. See airtime.

Century Dictionary and Cyclopedia

1. n. In ornithology, an air-cell of large size; an air-receptacle or a pneumatocyst (which see).
2. n. 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.
3. n. In firearms, a vacant space between the powder-charge and the projectile.

Wiktionary

1. n. 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.
2. n. aviation A designated part of the sky for aircraft use.
3. n. broadcasting Space (i.e. a few neighboring frequencies) available for broadcasting within a particular frequency band.
4. n. The portion of an enclosed area which contains air, especially breathable air.
5. n. construction The cavity in a cavity wall containing air for insulation.

GNU Webster's 1913

1. n. the atmosphere above a nation and deemed to be under its jurisdiction.

WordNet 3.0

1. n. the space in the atmosphere immediately above the earth
2. n. the atmosphere above a nation that is deemed to be under its jurisdiction
3. n. the space in the atmosphere immediately above the earth