The Collaborative International Dictionary of English v.0.48:

Saleratus \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 Aerated.] (Old Chem.)
   Aerated 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.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sodium bicarbonate \Sodium bicarbonate\,
   a white crystalline substance, HNaCO3, with a slight
   alkaline taste resembling that of sodium carbonate. It is
   found in many mineral springs and also produced
   artificially,. It is used in cookery, in baking powders, and
   as a source of carbonic acid gas (carbon dioxide) for soda
   water. Called also baking soda, cooking soda,
   bicarbonate of soda, bicarb, saleratus, and
   technically, acid sodium carbonate, sodium acid
   carbonate, primary sodium carbonate, sodium dicarbonate,
   etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

saleratus
    n 1: a white soluble compound (NaHCO3) used in effervescent
         drinks and in baking powders and as an antacid [syn:
         bicarbonate of soda, sodium hydrogen carbonate, sodium
         bicarbonate, baking soda, saleratus]