A collective expression for those components of the atmosphere that influence the greenhouse effect, namely carbon dioxide, methane, nitrous oxides, ozone, CFCs and water vapour. (Source: GEMET/GILP96)

A collective term, sometimes abbreviated GHG, used for any atmospheric infrared radiation produced by solar warming of the Earth's surface. They include carbon dioxide (CO2), methane (CH4), nitrous oxide (NO2), and water vapor. (Source: draft based on Wikipedia)