# Name for points with same value in a periodic function

I'm looking for a name to describe the points of the same value of a periodic function -- you draw a horizontal line across a periodic function and you get a set of values.

That is, a name for _all $x$ points where $\sin(x)=0$, for example. That would be the set of points $x=n\pi, n \in \mathbb{I}$. But is there a name to describe this set -- e.g. all the "isopoints" of $\sin(x)$ for a given value of $\sin(x)$?