What is the word goodbye mean in Islam?

In Arabic language, the most prominent and most used in Islam, you can say goodbye like you say hello: As-Salamu Alaykom, which is used to them like the Americans say: Peace, but in a more formal way. However, Islam is not a language it's a religion so it's like saying: How do you say goodbye in Christianity. As-Salamu Alaykom is the way the Prophet Muhammad, the role model of all Muslims, used to greet and say goodbye.