The Collaborative International Dictionary of English v.0.48:

Soda \So"da\, n. [It., soda, in OIt., ashes used in making
   glass, fr. L. solida, fem. of solidus solid; solida having
   probably been a name of glasswort. See Solid.]
   1. (Chem.)
      (a) Sodium oxide or hydroxide.
      (b) Popularly, sodium carbonate or bicarbonate. Sodium
          bicarbonate is also called baking soda
          [1913 Webster]

   2. same as sodium, used in terms such as bicarbonate of
      soda.
      [PJC]

   3. same as soda water.
      [PJC]

   4. a non-alcoholic beverage, sweetened by various means,
      containing flavoring and supersaturated with carbon
      dioxide, so as to be effervescent when the container is
      opened; -- in different localities it is variously called
      also soda pop, pop, mineral water, and minerals.
      It has many variants. The sweetening agent may be natural,
      such as cane sugar or corn syrup, or artificial, such as
      saccharin or aspartame. The flavoring varies widely,
      popular variants being fruit or cola flavoring.
      [PJC]

   Caustic soda, sodium hydroxide.

   Cooking soda, sodium bicarbonate. [Colloq.]

   Sal soda. See Sodium carbonate, under Sodium.

   Soda alum (Min.), a mineral consisting of the hydrous
      sulphate of alumina and soda.

   Soda ash, crude sodium carbonate; -- so called because
      formerly obtained from the ashes of sea plants and certain
      other plants, as saltwort (Salsola). See under Sodium.


   Soda fountain, an apparatus for drawing soda water, fitted
      with delivery tube, faucets, etc.

   Soda lye, a lye consisting essentially of a solution of
      sodium hydroxide, used in soap making.

   Soda niter. See Nitratine.

   Soda salts, salts having sodium for the base; specifically,
      sodium sulphate or Glauber's salts.

   Soda waste, the waste material, consisting chiefly of
      calcium hydroxide and sulphide, which accumulates as a
      useless residue or side product in the ordinary Leblanc
      process of soda manufacture; -- called also alkali
      waste.

   Washing soda, sodium carbonate. [Colloq.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Soda water \So"da wat`er\, n.
   1. originally, a beverage consisting of a weak solution of
      sodium bicarbonate to which an acid (such as phosphoric
      acid) has been added to generate carbon dioxide and thus
      cause effervescence; the term now is also used as a
      synonym for soda pop. Soda water without flavoring is
      used as a beverage or as a component of a mixed beverage.
      It is typically bottled or canned under pressure so that
      the carbon dioxide and effervescence will be preserved
      until use.
      [PJC]

   2. a beverage containing supersaturated carbon dioxide
      (carbonic acid) and thus effervescent.
      [PJC]

   3. same as soda pop.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Soda pop \So"da pop\, n.
   a popular non-alcoholic beverage, sweetened by various means,
   containing flavoring and supersaturated with carbon dioxide,
   so as to be effervescent when the container is opened; -- in
   different localities it is variously called also soda,
   pop, mineral water, and minerals. It has many variants.
   The sweetening agent may be natural, such as cane sugar or
   corn syrup, or artificial, such as saccharin or aspartame.
   The flavoring varies widely, popular variants being fruit
   juices, fruit sirups, cream, or cola flavoring; the soda pop
   is usually served chilled.

   Note: Several large corporations started primarily as
         bottlers of soda pop, such as Coca-Cola,
         Pepsi-Cola, and Dr. Pepper.
         [PJC]

WordNet (r) 3.0 (2006):

soda pop
    n 1: a sweet drink containing carbonated water and flavoring;
         "in New England they call sodas tonics" [syn: pop,
         soda, soda pop, soda water, tonic]