air·space / ˈe(ə)rˌspās/ • n. space available in the atmosphere immediately above the earth. ∎ the air available to aircraft to fly in, esp. the part subject to the jurisdiction of a particular country: the airliner was refused permission to enter Maltese airspace. ∎ Law the right of a private landowner to the space above his land and any structures on it, which he can use for ordinary purposes such as the erection of signposts. ∎ space left to be occupied by air for purposes of insulation.