A more thorough explanation:

Definition: An arrester is a person or device that stops or prevents something from moving or progressing further.

Example 1: A police officer is an arrester who stops criminals from committing crimes and puts them in jail.

Example 2: A lightning arrester is a device that protects buildings and other structures from lightning strikes by diverting the electrical current to the ground.

The examples illustrate the definition of an arrester by showing how it can refer to both a person and a device that stops or prevents something from happening. In example 1, a police officer is an arrester because they stop criminals from committing crimes and prevent them from causing harm to others. In example 2, a lightning arrester is a device that stops lightning from damaging buildings and other structures by diverting the electrical current away from them.