airway

(noun) a duct that provides ventilation (as in mines). Synonyms: air passage, air duct.

(noun) a designated route followed by airplanes in flying from one airport to another. Synonyms: air lane, flight path, skyway.

(noun) the passages through which air enters and leaves the body. Synonyms: respiratory tract.

(noun) a commercial enterprise that provides scheduled flights for passengers. Synonyms: airline, airline business.