A deed, action, or regular practice — used for evil deeds of the body that must be put to death and for the 'Acts' of the apostles.
The Greek praxis (from prassō, to do/practice) means an action, deed, or ongoing practice. It is a significant NT word: Romans 8:13 calls believers to 'put to death the praxeis of the body by the Spirit'; Colossians 3:9 commands putting off the 'old self with its praxeis'; Luke 23:51 describes Joseph of Arimathea as one 'who had not consented to their decision and action (praxis)'; and in Acts 19:18 new converts 'openly confessed what they had done (praxeis).' The word 'Acts' (Greek: Praxeis) in the title of Luke's second volume is the 'Deeds/Actions of the Apostles.'
The theology of praxis in Romans 8:13 is the heart of sanctification: 'if by the Spirit you put to death the praxeis of the body, you will live.' The body's habitual practices — the patterns of flesh — must be actively mortified, not merely regretted. Yet this is not human self-improvement: it is specifically 'by the Spirit' that the old praxeis are put to death. Sanctification is cooperative — the human will and the divine Spirit working together to replace old patterns with new ones. The book of Praxeis (Acts) shows what this looks like at scale: Spirit-empowered people enacting the ongoing deed of God in history.