ventilation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The replacement of stale or noxious air with fresh air.
• noun The mechanical system or equipment used to circulate air or to replace stale air with fresh air.
• noun The maintenance of breathing by artificial means.
• noun A breath that is induced by artificial means.

from The Century Dictionary.

• noun The act of fanning or blowing.
• noun The act or process of replacing foul or vitiated air, in any confined space, with pure air; the theory, method, or practice of supplying buildings, ships, mines, chimneys, air-shafts, etc., with pure air.
• noun Aëration of the blood or the body by means of respiratory organs; admission of air in respiration.
• noun The act of bringing to notice and discussion; public exposition; free discussion: as, the ventilation of abuses or grievances.
• noun Utterance; expression; vent.

from the GNU version of the Collaborative International Dictionary of English.

• noun 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.
• noun obsolete The act of refrigerating, or cooling; refrigeration.
• noun The act of fanning, or winnowing, for the purpose of separating chaff and dust from the grain.
• noun The act of sifting, and bringing out to view or examination; free discussion; public exposure.
• noun The act of giving vent or expression.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The replacement of stale or noxious air with fresh.
• noun The mechanical system used to circulate and replace air..
• noun An exchange of views during a discussion.
• noun The bodily process of breathing; the inhalation of air to provide oxygen, and the exhalation of spent air to remove carbon dioxide.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a mechanical system in a building that provides fresh air
• noun the bodily process of inhalation and exhalation; the process of taking in oxygen from inhaled air and releasing carbon dioxide by exhalation
• noun free and open discussion of (or debate on) some question of public interest
• noun the act of supplying fresh air and getting rid of foul air