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
2. (euphemism) the removal of a threat by killing or destroying it (especially in a covert operation or military operation)
3. action intended to keep a country politically neutral or exclude it from a possible war;
"the neutralization of Belgium"
4. action intended to nullify the effects of some previous action