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

口辺単純疱疹[kouhentanjunhoushin] cold sore
純愛[junai] pure love
純益[juneki] clear profit
純化[junka] purification
純金[junkin] pure gold

純潔[junketsu] purity
純血[junketsu] pure-bred (usu. animal)
純情[junjou] pure heart
純真[junshin] purity
純粋[junsui] pure