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

緩衝[kanshou] buffered
緩衝器[kanshouki] shock absorber
緩衝地帯[kanshouchitai] buffer zone
刺衝[shishou] stabbing
衝撃[shougeki] shock

衝撃波[shougekiha] shock wave
衝動[shoudou] impulse
衝動行為[shoudoukoui] shock action
衝動買い[shoudougai] impulsive buying
衝突[shoutotsu] collision