A more thorough explanation:

Definition: Eyre (air) is a historical system of royal courts that were sent out into the counties by the Crown to investigate allegations of wrongdoing, to try cases, and to raise revenue for the Crown through the levy of fines. The eyre system was abolished in the 14th century.

Example: In 1176, the itinerant justices were organized into six circuits. The justices assigned to these circuits, who numbered as many as twenty or thirty at a time in the 1180s, were known as justiciae errantes (later justiciarii in itinere, justices in eyre); and the French word ‘eyre’ became the name of one of the most prominent forms of royal justice until the time of Edward III.

Explanation: The example illustrates how the term "eyre" was used to refer to the system of royal courts that were sent out into the counties by the Crown to investigate allegations of wrongdoing, to try cases, and to raise revenue for the Crown through the levy of fines. It also shows how the term evolved over time to become one of the most prominent forms of royal justice until the time of Edward III.

Example: Every so often, a ‘general eyre’ would visit a county, bringing the king's government with it. The general eyres were not merely law courts; they were a way of supervising local government through itinerant central government.

Explanation: This example shows how the general eyres were used to supervise local government through itinerant central government. It also highlights the fact that the general eyres were not just law courts, but a way of bringing the king's government to the counties.