\Sal`e*ra"tus\, n. [NL. sal a["e]ratus; -- so called because it is a source of fixed air (carbon dioxide). See {Sal}, and and {A["e]rated}.] (Old Chem.) A["e]rated salt; a white crystalline substance having an alkaline taste and reaction, consisting of sodium bicarbonate (see under {Sodium}.) It is largely used in cooking, with sour milk (lactic acid) or cream of tartar as a substitute for yeast. It is also an ingredient of most baking powders, and is used in the preparation of effervescing drinks.