While this term refers to the entire basket of skills having to do with rotational movements of particular areas of the body while skiing, it also identifies a specific way of turning the skis.  Turning with rotation is achieved with an aggressive twisting of the upper body in the direction of the new turn.  Done during the transition between turns, that upper body twisting serves to twist the skis in the same direction.   It's a labor intensive means of turning the skis, that's often seen being used by skiers with a limited skill base.  While it does have situational use, even for the expert skier, there are more movement and energy efficient ways to turn the skis.