A more thorough explanation:

Triple ordeal is a type of trial that was used in the past to determine if someone was guilty or innocent of a crime. It involved subjecting the accused person to three dangerous or painful physical tests, with the result being considered a divine revelation of their guilt or innocence.

For example, a triple ordeal by water required the accused to submerge an arm into boiling water up to the elbow, while a single ordeal required the arm to be submerged only to the wrist. This was considered a more serious form of trial than a single ordeal, which was prescribed for someone accused of a less serious crime and involved less risk or torture.

The participants believed that God would reveal a person's culpability by protecting an innocent person from some or all consequences of the ordeal. The ordeal was commonly used in Europe until the 13th century, but only sporadically after 1215, when the Fourth Lateran Council forbade the clergy from participating in ordeals.

Overall, triple ordeal was a primitive form of trial that relied on divine intervention to determine guilt or innocence, and it was eventually replaced by other forms of trial, such as the criminal trial jury.