Hysteria is when someone has a very strong emotion that is unmanageable. Often, this means a very strong sense of fear. When someone has hysteria, it is called "hysterics". Hysteria could be caused by traumatic events in a person's life.
Today, many psychiatrists and other doctors do not use the word "hysteria" for a patient. They use other words that have the same meaning. Some of the words they may use are "psychosomatic", "functional", "nonorganic", "psychogenic", or "medically unexplained".