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

• air duct
• air passage

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

• air lane
• flight path
• skyway

3. (noun) the passages through which air enters and leaves the body

• respiratory tract

4. (noun) a commercial enterprise that provides scheduled flights for passengers

• airline
• airline business

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

• breather
• schnorchel
• schnorkel
• snorkel
• snorkel breather
• register
• upcast
• ventilation shaft

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

• approach
• approach path
• glide path
• glide slope
• holding pattern

3. (noun) the passages through which air enters and leaves the body

• lower respiratory tract
• upper respiratory tract

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

• duct

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

• itinerary
• path
• route

3. (noun) the passages through which air enters and leaves the body

• tract

4. (noun) a commercial enterprise that provides scheduled flights for passengers

• line

1. (noun) a commercial enterprise that provides scheduled flights for passengers

• airliner