An oval (from Latin ovum 'egg') is a closed curve in a plane which resembles the outline of an egg.
Generally, to be called an oval, a plane curve should resemble the outline of an egg or an ellipse.
Although the term egg-shaped usually implies a lack of reflection symmetry across the equatorial plane, it may also refer to true prolate ellipsoids.
In common speech, "oval" means a shape rather like an egg or an ellipse, which may be two-dimensional or three-dimensional.
It also often refers to a figure that resembles two semicircles joined by a rectangle, like a cricket infield, speed skating rink or an athletics track.