The Collaborative International Dictionary of English v.0.48:

Potassium \Po*tas"si*um\, n. [NL. See Potassa, Potash.]
   (Chem.)
   An Alkali element, occurring abundantly but always combined,
   as in the chloride, sulphate, carbonate, or silicate, in the
   minerals sylvite, kainite, orthoclase, muscovite, etc. Atomic
   weight 39.0. Symbol K (Kalium).
   [1913 Webster]

   Note: It is reduced from the carbonate as a soft white metal,
         lighter than water, which oxidizes with the greatest
         readiness, and, to be preserved, must be kept under
         liquid hydrocarbons, as naphtha or kerosene. Its
         compounds are very important, being used in glass
         making, soap making, in fertilizers, and in many drugs
         and chemicals.
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   Potassium permanganate, the salt KMnO4, crystallizing in
      dark red prisms having a greenish surface color, and
      dissolving in water with a beautiful purple red color; --
      used as an oxidizer and disinfectant. The name chameleon
      mineral is applied to this salt and also to potassium
      manganate.

   Potassium bitartrate. See Cream of tartar, under Cream.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cream \Cream\ (kr[=e]m), n. [F. cr[^e]me, perh. fr. LL. crema
   cream of milk; cf. L. cremor thick juice or broth, perh. akin
   to cremare to burn.]
   1. The rich, oily, and yellowish part of milk, which, when
      the milk stands unagitated, rises, and collects on the
      surface. It is the part of milk from which butter is
      obtained.
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   2. The part of any liquor that rises, and collects on the
      surface. [R.]
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   3. A delicacy of several kinds prepared for the table from
      cream, etc., or so as to resemble cream.
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   4. A cosmetic; a creamlike medicinal preparation.
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            In vain she tries her paste and creams,
            To smooth her skin or hide its seams. --Goldsmith.
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   5. The best or choicest part of a thing; the quintessence;
      as, the cream of a jest or story; the cream of a
      collection of books or pictures.
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            Welcome, O flower and cream of knights errant.
                                                  --Shelton.
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   Bavarian cream, a preparation of gelatin, cream, sugar, and
      eggs, whipped; -- to be eaten cold.

   Cold cream, an ointment made of white wax, almond oil, rose
      water, and borax, and used as a salve for the hands and
      lips.

   Cream cheese, a kind of cheese made from curd from which
      the cream has not been taken off, or to which cream has
      been added.

   Cream gauge, an instrument to test milk, being usually a
      graduated glass tube in which the milk is placed for the
      cream to rise.

   Cream nut, the Brazil nut.

   Cream of lime.
      (a) A scum of calcium carbonate which forms on a solution
          of milk of lime from the carbon dioxide of the air.
      (b) A thick creamy emulsion of lime in water.

   Cream of tartar (Chem.), purified tartar or argol; so
      called because of the crust of crystals which forms on the
      surface of the liquor in the process of purification by
      recrystallization. It is a white crystalline substance,
      with a gritty acid taste, and is used very largely as an
      ingredient of baking powders; -- called also potassium
      bitartrate, acid potassium tartrate, etc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

potassium bitartrate
    n 1: a salt used especially in baking powder [syn: cream of
         tartar, tartar, potassium bitartrate, potassium
         hydrogen tartrate]