\begin{definition}[Definition:Asymptote]
:500pxrightthumbAsymptotes to $y = x + \dfrac 1 x$ (blue): [[Definition:Y-Axis$y$-axis, and the line $x = y$ (red)]]
Let $C$ be a curve in the plane.
Let $L$ be a straight (infinite) line such that the distance between $C$ and $L$ approaches zero as they tend to infinity.
Then $L$ is an '''asymptote to''' (or '''of''') $C$.
\end{definition}