The quality of being eccentric or odd; any eccentric behaviour.
The ratio, constant for any particular conic section, of the distance of a point from the focus to its distance from the directrix.
The eccentricity of the conic section (usually an ellipse) defined by the orbit of a given object around a reference object (such as that of a planet around the sun).
A rare object.
A measure of the scarcity of an object.
Thinness; the property of having low density