A closed plane curve resulting from the intersection of a circular cone and a plane cutting completely through it WordNet 3.0 & Open English WordNet

An oval is a closed curve in a plane which resembles the outline of an egg. Wikipedia

In mathematics, an ellipse is a plane curve surrounding two focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant. Wikipedia

Curve resembling an egg or an ellipse. Wikipedia Disambiguation

A type of conic section in geometry Wikipedia Disambiguation

Type of curve on a plane Wikidata

Any curve resembling an egg or an ellipse. OmegaWiki

A curved planar figure, the locus of all points which have the same total distance from two fixed points called the foci. OmegaWiki

A closed curve, the locus of a point such that the sum of the distances from that point to two other fixed points (called the foci of the ellipse) is constant; equivalently, the conic section that is the intersection of a cone with a plane that does not intersect the base of the cone. Wiktionary

Curve. Wiktionary (translation)