# Oval

In geometry, an **oval** or **ovoid** (from Latin *ovum*, 'egg') is any curve resembling an egg or an ellipse. Unlike other curves, the term 'oval' is not well-defined and many distinct curves are commonly called ovals. These curves have in common that:

- they are differentiable (smooth-looking), simple (not self-intersecting), convex, closed, plane curves;
- their shape does not depart much from that of an ellipse, and
- there is at least one axis of symmetry.

The word ovoidal refers to the characteristic of being an ovoid.

Other examples of ovals described elsewhere include:

## Egg shape

The shape of an egg is approximately that of half each a prolate (long) and roughly spherical (potentially even minorly oblate/short) ellipsoid joined at the equator, sharing a principal axis of rotational symmetry, as illustrated above. Although the term *egg-shaped* usually implies a lack of reflection symmetry across the equatorial plane, it may also refer to true prolate ellipsoids. It can also be used to describe the 2-dimensional figure that, revolved around its major axis, produces the 3-dimensional surface.

## Projective planes

In the theory of projective planes, * oval* is used to mean a set of

*q*+ 1 non-collinear points in PG(2,q), the projective plane over the finite field with

*q*elements. See oval (projective plane).

## See also

de:Oval (Geometrie) it:Ovale ka:ოვალი lt:Ovalas nl:Ovaal simple:Oval sl:Oval (geometrija) sr:Овал