From a circle (any number of dancers) moving to the left: Drop hands and moving in the same direction, place right hands on the right shoulder ahead. On the next call ("Back by the left"), dancers right face turn to reverse direction and place left hands on left shoulders ahead and walk counterclockwise. Now each dancer with the right hand takes hold of the hand which is on his shoulder, raises it and makes an arch to duck under it and make a circle facing out. Continue moving the circle counterclockwise. One couple (a man and his original partner) will now be directed to make an arch, turn toward each other, back under their own arms and move the arch over the other dancers until all are facing toward the center again.
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.