Bible Dictionary
SEPARATION
Separation can describe ceremonial uncleanness under the Pentateuchal law or the setting apart associated with a Nazirite vow. Such separation marked a person or condition as distinct in relation to holiness.
Biblical Usage
In the Pentateuch, niddah points especially to ceremonial uncleanness. The related idea of nezer refers to the separation or consecration of the Nazirite. Purification, including the water of purification, was connected with cleansing what was ceremonially unclean.