From what I can gather, Prost is the colloquial form of Prosit. However, I’ve searched around quite a bit and I see all sorts of explanations. A lot of them explain it the same way, almost word-for-word, as that found on the Wikipedia page for toasts. However, I’ve also seen responses from people who say they are native Germans and they say they’ve never even heard the word Prosit.
So, even if we take the single-source Wikipedia explanation as true, what are the differences in usage? Is it simply that Prosit is old-fashioned and most people just say Prost, or is it regional (I seen some claim it is a Germany/Austria difference, and some suggest it is a Hochdeutsch/Bairisch difference)?
For what it’s worth, John Banner, who was born in Austria and came to the United States speaking only German, says Prosit several times on various episodes of Hogan’s Heroes. It is also the name of an oft-played song at Oktoberfest:
Ein Prosit, ein Prosit der Gemütlichkeit