One having in his custody persons accused of breaking the law; a prison keeper. Two Greek words are translated in the Scriptures as jailer: ba·sa·ni·stesʹ, meaning “tormentor,” and de·smo·phyʹlax, a compound of de·smosʹ (band, fetter) and phyʹlax (guard).

Jailers often inflicted cruel tortures on prisoners, hence were called ba·sa·ni·stesʹ. For example, debtors were sometimes thrown into prison for failing to pay what they owed. There the jailer might scourge and torture them, and they would not be released until, as Jesus said, they “paid over the last coin of very little value.” (Mt 5:25, 26) This also was the point of Jesus’ illustration about the unmerciful slave. When the master learned what his ungrateful slave had done, he “delivered him to the jailers [ba·sa·ni·staisʹ], until he should pay back all that was owing.”​—Mt 18:34, 35; compare Re 14:11, where “torment” is translated from ba·sa·ni·smouʹ.

If the prisoners escaped, jailers were held liable for the penalty imposed on the escapee, according to Roman custom. Hence, when Peter was set free from prison by an angel, we read that Herod “examined the guards and commanded them to be led off to punishment.”​—Ac 12:19.

In Philippi, Paul and Silas were dragged before the civil magistrates, who commanded that they be beaten with rods, and “after they had inflicted many blows upon them, they threw them into prison, ordering the jailer [de·smo·phyʹla·ki] to keep them securely. Because he got such an order, he threw them into the inner prison and made their feet fast in the stocks.” (Ac 16:22-24) Then in the middle of the night a great earthquake opened all the prison doors. This caused the jailer to imagine the prisoners had escaped, and realizing what severe punishment would be meted out to him if this were so, he was about to kill himself when Paul informed him that they were all there. These events, together with Paul’s instructions, caused this jailer to exercise faith, and he and his household became baptized believers.​—Ac 16:25-36.