Source : Webster's Revised Unabridged Dictionary (1913)

Lustral \Lus"tral\, a. [L. lustralis, fr. lustrum: cf. F.
   lustral. See {Lustrum}.]
   1. Of or pertaining to, or used for, purification; as,
      lustral days; lustral water.

   2. Of or pertaining to a lustrum.