Zirkel.

Etymology tree Proto-Indo-European *(s)ker-der. Ancient Greek κίρκος (kírkos)bor. Latin circus Proto-Indo-European *-nós Proto-Indo-European *-iHnos Proto-Italic *-īnos Latin -inus Latin circinusbor. ▲ Latin circulusinflu.? Old High German -ilinflu.? Old High German zirkil Middle High German zirkel German Zirkel From Middle High German zirkel, from Old High German zirkil, from Latin circinus (“pair of compasses”), from Ancient Greek κίρκινος (kírkinos). The Old High German -il is due to either alteration after the Germanic tool suffix *-ilaz, or confluence with Latin circulus (“circle”); the -k- speaks in favour of the latter explanation. The sense “circle”, which appears in Middle High German, is at any rate borrowed from circulus. Both Latin words ultimately go back to Ancient Greek κίρκος (kírkos).