The title pretty much says it all. I cannot find it in the glossary. And being a native German speaker does not help either¹.
The old woman studied Paul in one gestalten flicker: face oval like Jessica's, but strong bones . . . hair
From Dune, Book 1, chapter 1
¹If it helps anybody, the German noun Gestalten means forms, shapes, figures, while the verb gestalten means to shape, to create.