I'd guess the definition of "right-wing" slides along with the definition of "moderate" or "center" (and also "left-wing") in any particular place.
If the US is in general more right-leaning than Germany, then "right-wing" should also be farther right in the US than in Germany, yes?
It seems careless to compress political opinions into a single dimension stretching from "communist" on the extreme left to "fascist" on the extreme right.
I'm guessing this simplification holds up as well as it does because of a tendency for people's beliefs to cluster according to the weights they put on a few basic ideas of morality (and perhaps more fundamentally, whether they consider those ideas to be moral issues or not).
Jonathan Haidt gave an interesting TED talk about this ( http://www.ted.com/talks/jonathan_haidt_on_the_moral_mind.ht... ). He named five 'types' of morality: Harm, Fairness, Ingroup, Authority, and Purity. His thesis was that people on the left tend to value Harm and Fairness far above the other three, while on the right people tend to value all five roughly equally.