The Greek halusis (ἅλυσις) refers to a chain or shackle — the physical restraint used on prisoners. In the New Testament, the word appears primarily in descriptions of Paul's imprisonment and the Gerasene demoniac's chains. The word could denote both light chains for wrist restraint and heavier chains for maximum security prisoners.
The halusis (chain) becomes a paradoxical symbol of freedom in Paul's ministry. Paul refers to his chains in Ephesians 6:20, where he asks for prayer to "declare [the gospel] boldly, as I ought to speak" — his chains cannot silence the gospel. In Philippians 1:13, his chains have actually "served to advance the gospel," becoming known throughout the whole imperial guard. The image of Peter's chains falling off in Acts 12:7 is a dramatic depiction of divine liberation. The contrast between physical chains and spiritual freedom is central to Paul's theology of suffering: "The word of God is not chained" (2 Timothy 2:9). The demoniac's chains (Mark 5:4) that no one could break are shattered by Jesus — a picture of demonic bondage broken by Christ's authority.