The portion of an enclosed area which contains air, especially breathable air.
that part of the sky designated for the sole use of aircraft.
The cavity in a cavity wall containing air for insulation.
Space (i.e. a few neighboring frequencies) available for broadcasting within a particular frequency band.
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.
The upper atmosphere occupied by clouds, flying birds, etc.
The place above the Earth where God or other deities live; heaven.
The sky which appears to an observer on the Earth as a dome in which celestial bodies are visible; the firmament.