血清[kessei] serum
粛清[shukusei] (political) purge
真清水[mashimizu] pure water
清ます[sumasu] to clear
清む[sumu] to clear (e.g. weather)

清い[kiyoi] clear
清まる[kiyomaru] to be purified
清め[kiyome] purification
清める[kiyomeru] to purify
清らか[kiyoraka] clean

祓い清める[haraikiyomeru] to purify
お祓い[oharai] exorcism rite
修祓[shubatsu] purification rite (esp. one held prior to a Shinto event)
大祓い[ooharae] great purification
禊祓[misogiharae] form of Shinto purification

祓う[harau] to exorcise
名越しの祓[nagoshinoharae] summer purification rites (held at shrines on the last day of the 6th lunar month)
善祓[yoshiharae] purification to invite good fortune
悪祓[ashiharae] purification to cleanse one of sin