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

cation \cat"ion\, n. gr. ? downward + ? going, p. pr. of ? to
   go. chem.
   a positively charged atom, radical, or molecule, which in
   electrolysis migrates to the cathode; a positive ion; --
   opposed to anion. --faraday.
   1913 webster +pjc
see also:
anion 

[2] : WordNet (r) 2.0

cation
     n : a positively charged ion

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

51 moby thesaurus words for "cation":
   acid, acidity, agent, alkali, alkalinity, alloisomer, anion,
   antacid, atom, base, biochemical, chemical, chemical element,
   chromoisomer, compound, copolymer, dimer, electrocoating,
   electroetching, electrogalvanization, electrogilding,
   electrograving, electrolysis, electrolyte, electroplating, element,
   galvanization, heavy chemicals, high polymer, homopolymer,
   hydracid, inorganic chemical, ion, ionization, ionogen, isomer,
   macromolecule, metamer, molecule, monomer, neutralizer, nonacid,
   nonelectrolyte, organic chemical, oxyacid, polymer, pseudoisomer,
   radical, reagent, sulfacid, trimer

Cation >> C Words
Cation, definition of term: Cation
cation_pag1.html