A more thorough explanation:

Definition: A libellis is a term from Roman law that refers to an officer who is responsible for handling petitions (libelli) addressed to the emperor or sovereign. In modern times, it can also refer to the Chancellor of the Exchequer.

Example: In ancient Rome, a citizen who wanted to make a request or complaint to the emperor would write a libellus and submit it to the a libellis. The officer would then review the petition and decide whether to forward it to the emperor for consideration.

Explanation: The example illustrates how a libellis was responsible for managing the flow of petitions to the emperor. They acted as a gatekeeper, deciding which requests were worthy of the emperor's attention and which were not. In modern times, the term can also refer to the Chancellor of the Exchequer, who is responsible for managing the finances of the British government.