Plain English Meaning
A STAR is a printed flight path that guides arriving aircraft from cruise down toward the airport, using set waypoints and altitudes so pilots and controllers follow the same arrival pattern every time.
Full Definition
A standard terminal arrival route (STAR) is a published instrument flight rules (IFR) arrival procedure that provides a pre-planned route, with associated waypoints, altitudes, and speed restrictions, from the en route structure to a fix from which an approach to the destination airport can begin.