What does it mean to be a witness?

To be a witness is to be a bystander. To not be the victim nor the perpetrator. To be sitting on the sidelines and not affecting the outcome of a battle. Kind of like what America was during the holocaust. If you see someone bullying someone then don't be a witness, stop the bully and help the victim. This isn't the only thing being a witness means. If you are a witness of the holocaust then I think that it is your job to inform others of the horrific events that took place during that time.