(1):

(n.) The act of sifting, and bringing out to view or examination; free discussion; public exposure.

(2):

(n.) The act of ventilating, or the state of being ventilated; the art or process of replacing foul air by that which is pure, in any inclosed place, as a house, a church, a mine, etc.; free exposure to air.

(3):

(n.) The act of refrigerating, or cooling; refrigeration; as, ventilation of the blood.

(4):

(n.) The act of fanning, or winnowing, for the purpose of separating chaff and dust from the grain.

(5):

(n.) The act of giving vent or expression.