A more thorough explanation:

In legal proceedings, impertinent matter refers to information that is not relevant to the case or defense being presented. This can include irrelevant facts, arguments, or evidence that do not contribute to the resolution of the case.

For example, if a plaintiff is suing a defendant for breach of contract, any information about the defendant's personal life or unrelated business dealings would be considered impertinent matter. Similarly, if a defendant is claiming self-defense in a criminal case, any evidence about the victim's character or unrelated criminal history would be impertinent.

Impertinent matter can be struck from a pleading by a federal court, meaning it will not be considered in the case. This is because it can waste time and resources, and distract from the relevant issues at hand.