An ELLIPSE is a two-dimensional shape that is similar to an OVAL, but with two distinct differences. An ELLIPSE is a closed curve that is symmetrical about two focal points, while an OVAL is a closed curve that is symmetrical about one focal point. The term 'ELLIPSE' comes from the Greek word 'elipsis, ' which means 'OMISSION.' Ellipses are used in many areas of mathematics, including geometry, calculus, and trigonometry. They are also used in astronomy to describe the orbits of planets and other celestial bodies.