What is the meaning of Airspace?

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.

that part of the sky designated for the sole use of aircraft.

Space (i.e. a few neighboring frequencies) available for broadcasting within a particular frequency band.

The portion of an enclosed area which contains air, especially breathable air.

The cavity in a cavity wall containing air for insulation.

Source: wiktionary.org