mastix

This is the plain, physical meaning of the word: a whip, and the act of beating someone with it. In the Roman world the whip in view was a brutal instrument, often several weighted leather thongs braided together, and being flogged with it was used both as a punishment and as a way to force a confession out of a prisoner.

The New Testament uses this literal sense in two settings. In Acts a Roman officer is about to have Paul beaten in order to interrogate him, until Paul reveals he is a Roman citizen and stops it. In Hebrews the word appears in a roll call of faithful people who endured floggings rather than give up, language that deliberately recalls Jewish martyrs tortured for their faith. A closely related word is the temple whip Jesus made (φραγέλλιον), and the verb for the act of scourging is μαστιγόω.

The same word for a whip is turned onto sickness. When someone is spoken of as being freed from their "whip," the picture is of a disease striking the body the way a lash strikes the back, an affliction that comes down on a person from outside and torments them. This was not a new coinage but an old and widely shared way of speaking, in which severe suffering could be called a scourge.

This sense fills the Gospel uses. Mark uses it for the crowds pressing in to touch Jesus so their ailments might be healed, and twice for the woman with a chronic flow of blood, who feels in her body that she is freed from her affliction. Luke uses it in a summary of the many people Jesus healed of diseases and afflictions, where it is paired with the ordinary word for illness (νόσος) and seems to name the harsher, more tormenting cases. The word keeps the force of a blow even when what it names is an illness, which is why it is stronger and grimmer than a neutral word for being sick.