What is the opposite of peristalsis?

The opposite of peristalsis is a process known as "reflux" or "retroperistalsis." While peristalsis involves the coordinated contraction of muscles to move food and liquids through the digestive tract in a forward direction, reflux or retroperistalsis refers to the backward movement of contents, often seen in conditions like acid reflux or during vomiting. In essence, peristalsis facilitates forward movement, while its opposite results in backward movement.