Definition:Diameter of Central Conic/Also defined as

Definition
Some sources define the diameter of a central conic $\KK$ as a chord of $\KK$ which passes through the center of $\KK$.

This is a perfectly adequate definition of a diameter of an ellipse.

Indeed, in the context of a circle, this is how a diameter is routinely defined.

However, it falls short of providing a full definition of the diameter of a hyperbola.

Hence, for the general central conic, and one that is not specifically a circle, this definition is not used on.

Also see

 * Locus of Midpoints of Parallel Chords of Central Conic passes through Center


 * Definition:Diameter of Conic Section