[AIVC, Air infiltration and ventilation glossary, 1992]:the process of supplying or removing air, by natural or mechanical means to and from a space.

[ASHRAE 62.1]:the process of supplying outdoor air to or removing indoor air from a dwelling by natural or mechanical means. Such air may or may not have been conditioned.

[ASHRAE 62.2]:the process of supplying air to or removing air from a space for the purpose of controlling air contaminant levels, humidity, or temperature within the space.

[EN 16798-1:2019, 3.25]:process of providing outdoor air by natural or mechanical means to a space or building.

[EN 12792:2003, 388]:ventilation designed supply and removal of air to and from a treated space.
[ISO 16814:2008, 3.44]:process of supplying or removing air by natural means or mechanical means to or from a space for the purpose of controlling air contaminant levels, humidity, odours or temperature within the space.