The Collaborative International Dictionary of English v.0.48:

neutralisation \neutralisation\ n.
   Same as neutralization. [Chiefly Brit.]
   [WordNet 1.5]

WordNet (r) 3.0 (2006):

neutralisation
    n 1: a chemical reaction in which an acid and a base interact
         with the formation of a salt; with strong acids and bases
         the essential reaction is the combination of hydrogen ions
         with hydroxyl ions to form water [syn: neutralization,
         neutralisation, neutralization reaction,
         neutralisation reaction]
    2: (euphemism) the removal of a threat by killing or destroying
       it (especially in a covert operation or military operation)
       [syn: neutralization, neutralisation]
    3: action intended to keep a country politically neutral or
       exclude it from a possible war; "the neutralization of
       Belgium" [syn: neutralization, neutralisation]
    4: action intended to nullify the effects of some previous
       action [syn: neutralization, neutralisation,
       counteraction]