[AIVC, Air infiltration and ventilation glossary, 1992]:the mass/volume of air moved between two points.[EN 12792:2003, 19]:movement of air usually within boundaries (such as ducts)

[EN 12792:2003, 21]:component used to control the air flow rate by modifying the resistance(see also damper (or valve))

[EN 12792:2003, 304]:mass or volume of air entering a supply air terminal device in unit time from an upstream duct or a plenum box. It can also be the air leaving through an opening and entering a space.