The heretic's fork was a torture device, loosely consisting of a length of metal with two opposed bi-pronged "forks" as well as an attached belt or strap.
The device was placed between the breast bone and throat just under the chin and secured with a leather strap around the neck, while the victim was hung from the ceiling or otherwise suspended in a way so that they could not lie down. A person wearing it couldn't fall asleep. The moment their head dropped with fatigue, the prongs pierced their throat or chest, causing great pain. This very simple instrument created long periods of sleep deprivation. People were awake for days, which made confessions more likely.
Traditionally, the fork was engraved with the Latin word abiuro (meaning "I recant"), and was used by the various Inquisitions.
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