lustral

Of or pertaining to (ritual) purification.

So the men change along my changeless stream, And change their faiths; but I yield all alike Sweet water for their drinking, sweet as wine, And pure sweet water for their lustral rites: For thirty generations of my corn Outlast a generation of my men, And thirty generations of my men Outlast a generation of their gods.

lustral days

Of or relating to a lustrum, or period of five years.

a lustral cycle

Synonym of Zoloft.