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:

Sodium \So"di*um\, n. [NL., fr.E. soda.] (Chem.)
   A common metallic element of the alkali group, in nature
   always occuring combined, as in common salt, in albite, etc.
   It is isolated as a soft, waxy, white, unstable metal, so
   highly reactive that it combines violently with water, and to
   be preserved must be kept under petroleum or some similar
   liquid. Sodium is used combined in many salts, in the free
   state as a reducer, and as a means of obtaining other metals
   (as magnesium and aluminium) is an important commercial
   product. Symbol Na (Natrium). Atomic weight 22.990.
   Specific gravity 0.97.
   [1913 Webster]

   Sodium amalgam, an alloy of sodium and mercury, usually
      produced as a gray metallic crystalline substance, which
      is used as a reducing agent, and otherwise.

   Sodium carbonate, a white crystalline substance,
      Na2CO3.10H2O, having a cooling alkaline taste, found in
      the ashes of many plants, and produced artifically in
      large quantities from common salt. It is used in making
      soap, glass, paper, etc., and as alkaline agent in many
      chemical industries. Called also sal soda, washing
      soda, or soda. Cf. Sodium bicarbonate, and Trona.


   Sodium chloride, common, or table, salt, NaCl.

   Sodium hydroxide, a white opaque brittle solid, NaOH,
      having a fibrous structure, produced by the action of
      quicklime, or of calcium hydrate (milk of lime), on sodium
      carbonate. It is a strong alkali, and is used in the
      manufacture of soap, in making wood pulp for paper, etc.
      Called also sodium hydrate, and caustic soda. By
      extension, a solution of sodium hydroxide.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Washing \Wash"ing\, n.
   1. The act of one who washes; the act of cleansing with
      water; ablution.
      [1913 Webster]

   2. The clothes washed, esp. at one time; a wash.
      [1913 Webster]

   3. (Mining) Gold dust procured by washing; also, a place
      where this is done; a washery.
      [Webster 1913 Suppl.]

   4. A thin covering or coat; as, a washing of silver.
      [Webster 1913 Suppl.]

   5. (Stock Exchanges) The operation of simultaneously buying
      and selling the same stock for the purpose of manipulating
      the market. The transaction is fictitious, and is
      prohibited by stock-exchange rules.
      [Webster 1913 Suppl.]

   6. (Pottery) The covering of a piece with an infusible
      powder, which prevents it from sticking to its supports,
      while receiving the glaze.
      [Webster 1913 Suppl.]

   Washing bear (Zool.), the raccoon.

   Washing bottle (Chem.), a bottle fitted with glass tubes
      passing through the cork, so that on blowing into one of
      the tubes a stream of water issuing from the other may be
      directed upon anything to be washed or rinsed, as a
      precipitate upon a filter, etc.

   Washing fluid, a liquid used as a cleanser, and consisting
      usually of alkaline salts resembling soaps in their
      action.

   Washing machine, a machine for washing; specifically, a
      machine for washing clothes.

   Washing soda. (Chem.) See Sodium carbonate, under
      Sodium.

   Washing stuff, any earthy deposit containing gold enough to
      pay for washing it; -- so called among gold miners.
      [1913 Webster]

WordNet (r) 3.0 (2006):

washing soda
    n 1: a sodium salt of carbonic acid; used in making soap powders
         and glass and paper [syn: sodium carbonate, washing
         soda, sal soda, soda ash, soda]