The Collaborative International Dictionary of English v.0.48:

Lustrate \Lus"trate\, v. t. [imp. & p. p. Lustrated; p. pr. &
   vb. n. Lustrating.] [L. lustratus, p. p. of lustrare to
   lustrate, fr. lustrum. See Lustrum.]
   To make clear or pure by means of a propitiatory offering; to
   purify.
   [1913 Webster]

         We must purge, and cleanse, and lustrate the whole
         city.                                    --Hammond.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lustrate
    v 1: purify by means of a ritual; also used in post-Communist
         countries to refer to the political cleansing of former
         officials