Accusation comes from the verb accuse, which means to charge someone with a crime. It is important to remember that an accusation comes about when someone thinks another person has done something wrong or committed a crime. It doesn't mean, however, that the person is guilty.

What is it called when you falsely accuse someone?

False accusations are also known as groundless accusations or unfounded accusations or false allegations or false claims. ...

When you accuse someone of something are you guilty of?

From Wikipedia: The phrase "The pot calling the kettle black" is an idiom used to claim that a person is guilty of the very thing of which they accuse another.