Definition:Diameter of Ellipse/Also defined as

Definition
Let $\KK$ be an ellipse.

A diameter of $\KK$ is a chord of $\KK$ which passes through the center of $\KK$:


 * Diameters-of-ellipse.png

In the above diagram, $AB$, $CD$ and $EF$ are diameters of $\KK$.

Also see

 * Equivalence of Definitions of Diameter of Central Conic