In Czech there are many different ways or phrases on how to greet people. Ahoj is an informal greeting used both when meeting and parting with friends. Now if you think this nautical expression is out of place in a land-locked country, you're absolutely right. Nevertheless, the greeting, which found its way into the language in the 1920's together with expressions concerning sport, hiking, and camping is very popular among all generatons.
The general formal daytime greeting, used from morning until late is dobry den, meaning literally 'good day'. That's what Czechs say when they meet a stranger, somebody older, or somebody of higher status. The same applies to dobre rano or 'good morning', only this greeting is usable only until about 10 a.m. Even earlier than that, Czechs greet each other with dobre jitro. The word jitro means early morning, and as Czechs are known as early risers, this expression is actually quite frequent. In the afternoon, Czechs say dobre odpoledne or 'good afternoon', and in the evening they greet each other with dobry vecer. When parting at night or when going to bed, they say dobrou noc or 'good night'.
Friends, family or people who are on the first name terms have a different set of greetings they use among themselves. We've already spoken about ahoj. There's another originally foreign expression - cau, from the Italian. It, too, can be used both when meeting and parting with a friend. The Czech expression nazdar, is of Slavonic origin, and is linked to the verb darit se, to do well, or prosper. Often, you can hear a very intimate parting word pa, or papa. Originally, this term comes from baby-talk.
The formal greeting used when parting is na shledanou. It roughly means 'until we meet again' or 'see you'. Sometimes you can hear the abbreviated form nashle which is quite informal and somewhat less polite. Radio presenters often use an alteration of na shledanou which is na slysenou, meaning 'until we hear each other again'.
-Pavla Horakova
Radio Prague
Bureaucracy of the Czech Republic