WeirdWorld
"Hexenringe" means "witches' rings" in german.
If it's just a single ring the correct spelling would be "Hexenring".
Based on the fact that the one we see is referred to as, "an S Class Hexenringe," it is likely the monster's "species" name, and not the individual's name. After all, the kids call it Hex, which could be short for either, or the individual Hexenringe's name.
Additionally, while it might be one ring, it can create rings to channel it's powers through, like we saw when it teleported Charlie to S.I.N's base of operations, and how it is implied that there would be one near monster Deryl, so it maybe a reference to how it controls multiple rings.