Heisenberg uncertainty principle in German

It is called the « Unschärferelation ». Some people prefer that to the english version because uncertainty makes you think that if you made better measurements, you wouldn’t get this uncertainty, which is not the case. In fact, it is better to think about it as relation between the dispersion of the momentums and the dispersion of the positions of a particle, which product has to be greater than $\frac{\hbar}{2}$. In other words it is all about the relation of the unsharpness of these two distributions. That’s why « unsharpness relation » seems two describe it better than « uncertainty principle ».

In addition to Nicolas Schmid's answer, some but very few people use "Heisenbergsche Unbestimmtheitsrelation" for uncertainty relation but it actually means "indeterminacy relation". It makes a good sense though since there's an underlying indeterministic structure in quantum mechanics.