1. a duct that provides ventilation (as in mines)

Definition categories: man–made, duct

2. a designated route followed by airplanes in flying from one airport to another

Similar word(s): skyway

Definition categories: location, itinerary, path, route

3. the passages through which air enters and leaves the body

Definition categories: body, tract

4. a commercial enterprise that provides scheduled flights for passengers

Similar word(s): airline

Definition categories: man–made, line