Air hole
Air hole (âr" hōl`)
1.
A hole to admit or discharge air; specifically, a spot in the ice not frozen over.
2.
(Founding) A fault in a casting, produced by a bubble of air; a blowhole.
3.
(Aeronautics) A local region in the atmosphere having a downward movement and offering less than normal support for the sustaining surfaces of a flying machine, causing an airplane to drop suddenly. Same as air pocket.