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(from Latin lustratio, "purification by sacrifice"), any of various processes in ancient Greece and Rome whereby individuals or communities rid themselves of ceremonial impurity (e.g., bloodguilt, pollution incurred by contact with childbirth or with a corpse) or simply of the profane or ordinary state, which made it dangerous to come into contact with sacred rites or objects. The methods varied from sprinkling with or washing in water, through rubbing with various substances, such as blood or clay, to complicated ceremonies, some of which involved confession of sins. Fumigation was also used.