noun
: a heavy colorless gas CO 2 that does not support combustion, that dissolves in water to form carbonic acid, that is formed especially by the action of acids on carbonates, by the fermentation of liquors, and by the combustion and decomposition of organic substances (as in animal respiration, in the decay of animal and vegetable matter, and in the explosion of firedamp in mines), that is absorbed from the air by plants in the first step in photosynthesis, and that is used in the gaseous and liquefied forms chiefly in the carbonation of beverages, in fire fighting, in therapeutical work, in mining operations, in the chemical industry, and as a source of power (as in spray painting and inflating life rafts) and in the solidified form as dry ice — called also carbonic acid gas ; see afterdamp , blackdamp