ˈ ̷ ̷ˌ ̷ ̷ noun
1. : a passage for a current of air often underground (as in a mine)
2. : a designated route along which aircraft fly from airport to airport ; especially : such a route equipped with navigational aids
3. : air line 3
4. : a passageway for air into or out of the lungs ; specifically : a device passed into the trachea by way of the mouth or nose or through an incision to maintain a clear respiratory passageway (as during anesthesia, convulsions, or in obstructive laryngitis)
5. : a channel of a designated radio frequency for broadcasting or other radio communication