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 in an upright position from the ceiling or otherwise suspended in a way so that they could not lie down. Usually the Heretic's fork was given to blasphemers, liars, or people who spoke the lord's name in vain. This way, the punishment made it nearly impossible for them to talk. Also, 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. The victim would be awake for days, which made confessions more likely to happen.
Traditionally, the fork was engraved with the Latin word abiuro (meaning "I recant"), and was used by the various Inquisitions.