A more thorough explanation:

Definition: In historical English law, an appellor was a person who formally accused another of a crime, challenged a jury, or informed against an accomplice.

Example: If someone witnessed a crime and reported it to the authorities, they could be considered an appellor.

Explanation: An appellor was someone who brought accusations against another person in a legal setting. This could include reporting a crime they witnessed, challenging the selection of a jury, or providing information about someone who was involved in a crime. The example illustrates how someone who reports a crime they witnessed could be considered an appellor.