Refers to ritual or spiritual purification, often in Shinto contexts, but can also be used more generally for cleansing something of impurities.
I received purification salt at the shrine.
There is a practice of standing under a waterfall for spiritual purification.
purifying salt
purifying salt (thrown before a sumo bout)
Standard kanji spelling for purification.
Alternate kanji spelling, less common but still used.
Derived from the verb 清める (きよめる, to purify), which itself comes from the adjective 清い (きよい, pure).