[1] : The Collaborative International Dictionary of English v.0.48

alkali \al"kali\ ?; 277, n.; pl. alkalis or alkalies. f.
   alcali, ultimately fr. ar. alqalimac ashes of the plant
   saltwort, fr. qalay to roast in a pan, fry.
   1. soda ash; caustic soda, caustic potash, etc.
      1913 webster

   2. chem. one of a class of caustic bases, such as soda,
      potash, ammonia, and lithia, whose distinguishing
      peculiarities are solubility in alcohol and water, uniting
      with oils and fats to form soap, neutralizing and forming
      salts with acids, turning to brown several vegetable
      yellows, and changing reddened litmus to blue.
      1913 webster

   3. soluble mineral matter, other than common salt, contained
      in soils of natural waters. western u. s.
      webster 1913 suppl.

   fixed alkalies, potash and soda.

   vegetable alkalies. same as alkaloids.

   volatile alkali, ammonia, so called in distinction from the
      fixed alkalies.
      1913 webster
see also:
alkalis alkalies fixed alkalies vegetable alkalies alkaloids volatile alkali 

[2] : WordNet (r) 2.0

alkali
     n 1: any of various water-soluble compounds capable of turning
          litmus blue and reacting with an acid to form a salt and
          water; "bases include oxides and hydroxides of metals
          and ammonia" syn: base
     2: a mixture of soluble salts found in arid soils and some
        bodies of water; detrimental to agriculture
     also: alkalies pl
see also:
base alkalies 

[3] : Moby Thesaurus II by Grady Ward, 1.0

39 moby thesaurus words for "alkali":
   acid, acidity, agent, alkalinity, alloisomer, anion, antacid, atom,
   base, biochemical, cation, chemical, chemical element,
   chromoisomer, compound, copolymer, dimer, element, heavy chemicals,
   high polymer, homopolymer, hydracid, inorganic chemical, ion,
   isomer, macromolecule, metamer, molecule, monomer, neutralizer,
   nonacid, organic chemical, oxyacid, polymer, pseudoisomer, radical,
   reagent, sulfacid, trimer

Alkali >> A Words
Alkali, definition of term: Alkali
alkali_pag1.html

Alkali Metal >> A Words
Alkali Metal, definition of term: Alkali Metal
alkali+metal_pag1.html