\begin{definition}[Definition:Conjugate Points (Geometry)]
Let $\CC$ be a circle.
Let $P$ and $Q$ be points in the plane of $\CC$.
Let:
:$P$ lie on the polar of $Q$
:$Q$ lie on the polar of $P$.
$P$ and $Q$ are known as '''conjugate points with respect to $\CC$.
\end{definition}