Witch 101: Deosil or Widdershins?
I love the use of archaic(that is, really darned old and not in common use anymore) terms in practice of Witchcraft – I think it gives us a feeling of connection to the Witches who have gone before us. But it can get confusing, too. Two of the most apt-to-befuddle terms are deosil and widdershines(also sometimes seen as windershins). These are both used to tell us which direction to turn in when we are moving in circle. Deosil means to turn clockwise or sunwise. Widdershins is the opposite, or counterclockwise.
Almost all movement inside a magickal circle is done deosil. We cast the circle moving to the right, and once in circle we continue to move in that direction–so that if you get up to go to the altar, for instance, you then continue moving all the way around the circle until you come back to your place. Widdershins is only used to undo things, so it may be used at the end of a ritual to open the circle space or in doing any magick for undoing(such as unbinding spells).
Source
Everyday Witch A to Z
Deborah Blake
Witches Of The Craft® 