1. The process of exposing to air: Janet hung out her blouse for aeration in order to get rid of some of the cigarette smoke from the evening before.
2. The charging of a liquid with air or other gas: Aeration takes place by the oxygenation of blood in the bronchial alveoli.
3. The act of charging a liquid with a gas making it effervesce: Jack wanted to have his water bubbly, so he used the process of aeration to achieve this purpose.

Aeration of waste water and industrial discharges by physical means: Mechanical aeration is the agitation of waste material from manufacturing companies by the use of paddle wheels, mixers, or rotating brushes.

The absorption of oxygen through the surface of a fluid: Susan learned that surface aeration applied to the entrainment of air bubbles that have not been dissolved and air pockets that are transported along with the liquid. The water and air mixture is comprised of little air packages inside the water and tiny water drops encircled by air.