ventilation (
http://definr.com/ventilation)
n 1: the act of supplying fresh air and getting rid of foul air
[syn:
airing]
2: a mechanical system in a building that provides fresh air;
"she was continually adjusting the ventilation" [syn: {ventilation
system},
ventilating system]
3: the process of taking in oxygen from inhaled air and
releasing carbon dioxide by exhalation [syn:
breathing,
external respiration]