Purification or purification ceremony. It can have the same range of meanings as Harai/Harae but refers especially to the use of salt water (or fresh water, cold or warm, or just salt) to remove tsumi or kegare, sins and pollution. At the simplest level misogi is practiced by shrine visitors who rinse their hands and mouth (temizu) on entering the shrine, or in the ceremony of shubatsu where purifying water (or salt) is sprinkled on priests or participants in a rite or on the ground for a matsuri. Most customary purifying practices involving salt or water including the long-established Japanese habit of regular bathing and the salt-sprinkling in the SumO dohyo (arena) are related to misogi. In some cases, priests may drench or immerse themselves in water before a ceremony. Such vigorous forms of misogi (shubatsu or kessai) are related to the Buddhist practices of mizugori or suigyo, cold water austerities which involve pouring buckets of freezing water over one's body or standing under a powerful waterfall, often in the dead of winter, in order to attain spiritual strength or shamanistic abilities. The use of natural or artificial waterfalls for suigyo is widespread among all kinds of religious fraternities in Japan. The mythological origin of misogi is said to be the purification of Izanagi no mikoto who according to the Nihongi and Kojiki cleansed himself in the sea after his horrifying and polluting visit to Yomi. From his garments and bathing were created numerous kami of purification, the misogi-harai-no-kami.
A Popular Dictionary of Shinto. Brian Bocking.