A backflow is a flow of a liquid in a direction opposite to that which is intended.

The semilunar valves prevent backflow into the ventricles. The pulmonary semilunar valve prevents backflow in the right ventricle, and the aortic semilunar valve prevents backflow of blood in the left ventricle.

The word backflow in terms of plumbing refers to an unwanted flow of water in the wrong direction. The risk of a contamination of clean water is prevented by backflow prevention devices.

the critical level of a backflow preventer is the point at which the outgoing pressure exceeds the incoming pressure

yes !