airport n.1

c. 1300, "invisible gases that surround the earth," from Old French air "atmosphere, breeze, weather" (12c.), from Latin aer "air, lower atmosphere, sky," from Greek aēr (genitive aeros) "mist, haze, clouds," later "atmosphere" (perhaps related to aenai "to blow, breathe"), which is of unknown origin. It is possibly from a PIE *awer- and thus related to aeirein "to raise" and arteria "windpipe, artery" (see aorta) on notion of "lifting, suspended, that which rises," but this has phonetic difficulties.

In Homer mostly "thick air, mist;" later "air" as one of the four elements. Words for "air" in Indo-European languages tend to be associated with wind, brightness, sky. In English, air replaced native lyft, luft (see loft (n.)). In old chemistry, air (with a qualifying adjective) was used of any gas.

To be in the air "in general awareness" is from 1875; up in the air "uncertain, doubtful" is from 1752. To build castles in the air "entertain visionary schemes that have no practical foundation" is from 1590s (in 17c. English had airmonger "one preoccupied with visionary projects"). Broadcasting sense (as in on the air, airplay) is by 1927. To give (someone) the air "dismiss" is from 1900. Air pollution is attested by 1870. Air guitar is by 1983. Air traffic controller is from 1956.

"a bay, cove, inlet, or recess of a large body of water where vessels can load and unload and find shelter from storms; a harbor, whether natural or artificial," Old English port "a port, harbor, a place where there is a constant resort of vessels for the purpose of loading and unloading;" also "a town, market town, city," reinforced by Old French port "harbor, port; mountain pass." The Old English and Old French words both are from Latin portus "a port, harbor," figuratively "haven, place of refuge, asylum" (in Old Latin also "a house;" in Late Latin also "a warehouse"), originally "an entrance, a passage," akin to porta "a city gate, a gate, a door" (from PIE *prtu- "a going, a passage," suffixed form of root *per- (2) "to lead, pass over").

[I]in law, a place where persons and merchandise are allowed to pass into and out of the realm and at which customs officers are stationed for the purpose of inspecting or appraising imported goods. In this sense a port may exist on the frontier, where the foreign communication is by land. [Century Dictionary]

The figurative sense "place, position, or condition of refuge" is attested in English from early 15c.; phrase any port in a storm, indicating "any refuge is welcomed in adversity," is by 1749. A port of call (1810) is one paid a scheduled visit by a vessel in the course of its voyage. The verb meaning "to carry or bring into a port" is by 1610s.