Fun fact: Servus was the most common greetings in Austria-Hungary, and it is still used in most of the successor states. In some countries it's considered archaic, but in Hungary it's still one of the most common informal greetings, sometimes pronounced with a "B" instead of "V" e.g. "serbus".

It's originally from latin, from the phrase servus humillimus, domine spectabilis meaning your most humble servant, my noble lord