\begin{definition}[Definition:Neighborhood of Infinity (Complex Analysis)]
A '''neighborhood of $\infty$''' in $\C$ is a subset of the set of complex numbers $\C$ wich contains a set of the form $\{z \in \C : |z| > r\}$ for some $r\in\R$.
That is, a subset which contains all complex numbers whose modulus is sufficiently large.
\end{definition}