How do you spell Aeration

Available Definitions:
1)  n. - Exposure to the free action of the air; airing; as, aeration of soil, of spawn, etc.
2)  n. - A change produced in the blood by exposure to the air in respiration; oxygenation of the blood in respiration; arterialization.
3)  n. - The act or preparation of charging with carbonic acid gas or with oxygen.