A more thorough explanation:

Definition: Brutum fulmen is a Latin phrase that means "a harmless thunderbolt." It refers to something that appears to be powerful or threatening, but is actually ineffective or meaningless.

Example: When the politician made his speech, he promised to make big changes, but it turned out to be a brutum fulmen because he didn't follow through on any of his promises.

Explanation: In this example, the politician's speech seemed powerful and promising, but it was actually meaningless because he didn't take any action to make the changes he promised. The phrase brutum fulmen is used to describe situations like this, where something appears to be powerful or threatening, but is actually harmless.