Deosil or deiseal means Sunwise or Clockwise.
The term is from Scottish folklore. Moving sunwise is considered lucky and safe while walking widdershins is unlucky. Thus, if you need to walk around a building to get to the door, you should always walk sunwise, keeping the building to your right. A circle, drawn sunwise or deosil around a house, stable or other building using a burning brand or torch is said to protect it from fire and malicious magick. Likewise, similar rituals might be performed for babies and mothers soon after birth to ensure the infants are not stolen by faeries or otherwise succumb to the myriad misfortunes that can fall upon a woman and child at this delicate time.
Many modern magickal practitioners prefer to perform ceremonial movements in a sunwise motion.