Easton's Bible Dictionary
The process by which a person unclean, according to the Levitical law, and thereby cut off from the sanctuary and the festivals, was restored to the enjoyment of all these privileges.
The great annual purification of the people was on the Day of Atonement (q.v.).
But in the details of daily life there were special causes of cermonial uncleanness which were severally provided for by ceremonial laws enacted for each separate case. For example, the case of the leper (Leviticus 13, 14), and of the house defiled by leprosy (14:49-53; see also Matthew 8:2-4). Uncleanness from touching a dead body (Numbers 19:11; Hosea 9:4; Haggai 2:13; Matthew 23:27; Luke 11:44). The case of the high priest and of the Nazarite (Leviticus 21:1-4, 10, 11; Numbers 6:6, 7; Ezek. 44:25). Purification was effected by bathing and washing the clothes (Leviticus 14:8, 9); by washing the hands (Deuteronomy 21:6; Matthew 27:24); washing the hands and feet (Exodus 30:18-21; Hebrews 6:2, "baptisms", R.V. marg., "washings;9:10); sprinkling with blood and water (Exodus 24:5-8; Hebrews 9:19), etc. Allusions to this rite are found in Psalm 26:6; 51:7; Ezek. 36:25; Hebrews 10:22.
Noah Webster's New International Dictionary of the English Language
1. (n.) The act of purifying; the act or operation of separating and removing from anything that which is impure or noxious, or heterogeneous or foreign to it; as, the purification of liquors, or of metals.
2. (n.) The act or operation of cleansing ceremonially, by removing any pollution or defilement.
3. (n.) A cleansing from guilt or the pollution of sin; the extinction of sinful desires, appetites, and inclinations.