Katharizō (G2511) means to cleanse, purify, or make clean — physically, ceremonially, or morally. Jesus used it when cleansing lepers (an act that restored them to community); the Holy Spirit applies it to the conscience and the heart.
The leper's cry 'Lord, if you are willing, you can make me clean (katharisai)' (Matthew 8:2) and Jesus' willing touch encapsulates the gospel: the untouchable made clean by sovereign grace. 1 John 1:9 anchors the believer's ongoing cleansing in confession: 'He is faithful and righteous to cleanse us from all unrighteousness.' The ultimate cleansing is by the blood of Christ (Hebrews 9:14).