The other day, I was having lunch at a nearby canteen near where I work. One of the things the canteen offered was a Kartoffelburger mit Matjesfillet und Buntsalat (Potato burger with herring fillets and salad). This turned out to be two potato patties, made by shredding potatoes and frying them, and in between are two herring fillets, sandwiched between these two potato patties, together with some sauce. This made me wonder and scratch my head a little, because for some reason, I had the idea that they were using the word burger a little bit different here. In fact, I thought that they were over-extending the meaning of the word burger.
See, the word burger resulted from an incorrent analysis of the word hamburger: people thought that hamburger is a composite word composed of the morphemes ham and burger. Hence, you find new words like fish burger, lamb burger, and chicken burger, all referring to food items where the named meat is prepared and presented between two slices of bread.
In actuality, though, hamburger comes from the adjectival form of Hamburg, which means "(a person or thing) from Hamburg". But then, perhaps only linguists or German speakers (and most likely German-speaking linguists) would know that for sure.
But recently, as evidenced by my most recent experience with a potato burger, there seemed to be a new trend extending the semantics of the word burger. It used to mean any meat sandwiched between two bread pieces, but now, even the bread can go away. When I saw the word Kartoffelburger I thought that I would see two bread pieces, and in between is a piece of potato. But no, in this case, the potato substitutes for the bread, and something else comes in between, in this case, herring fillets. I actually saw the same thing in Köln, when I visited last April. I was in a restaurant with colleagues and I ordered the Reibekuchenburger: a Reibekuchen is the local name for shredded potato patties, and the Reibekuchenburger consists of two of such patties, and in between is a piece of steak, some vegetables, and a fried egg.
These uses of the word burger definitely extends its semantics, in my opinion. Not to mention the fact that these new uses of the word burger also erases what in my opinion was a defining characteristic of what a real burger is, that one should eat it with one's own hands.
I suppose I am forgetting the fact that Germans are a very formal bunch, and even if they like going to burger restaurants in order to experience some American food, they eat their burgers using a fork and knife, as opposed to clutching it with their own two hands. In the case of these potato burgers, one cannot eat them using one's hands, instead, the fork and knife definitely has to be used.
I wonder what people would call as burgers fifty years from now. I am not necessarily against linguistic innovation, but sometimes I still catch myself being surprised at how a word changes its meaning.