Over 620 atmospheric chemistry terms which are in common use by the international research community in the atmospheric sciences are defined. The diversified nature of the scientists involved in research in atmospheric chemistry (chemists, meteorologists, physicists, biologists, engineers, and others) requires that special attention be paid to the consistency of the terminology employed. Where alternative terms are in common use to describe a given process, piece of equipment, feature, or quantity used in atmospheric chemistry, recommended choices of the IUPAC Commission on Atmospheric Chemistry are given; these are consistent with the other IUPAC publications and recommendations on nomenclature. The range of terms includes composition of the atmosphere, clouds, solar radiation, chemical and physical changes in atmospheric components, instrumentation employed in analysis of the atmospheric components and in air quality control, and in effects of certain trace gases on materials, plants, and animals.