Widdershins [widd-er-shins] is an adverb meaning "in a counterclockwise direction."
Find my sample sentence (5th paragraph) here. Also, as a note, when writing fantasy that includes magic/k, understand that direction is mighty important. When something travels "widdershins" it foreshadows the idea that a good spell (like Jennet's circle of protection) may be undone by dangerous forces. I hope that makes sense to you.