lustration
  清淨,潔淨
  Lus·tra·tion n.
  1. The act of lustrating or purifying.
     And holy water for lustration bring.   --Dryden.
  2. Antiq. A sacrifice, or ceremony, by which cities, fields, armies, or people, defiled by crimes, pestilence, or other cause of uncleanness, were purified.
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