\begin{definition}[Definition:Isolated Point (Topology)/Subset/Definition 2]
Let $T = \struct {S, \tau}$ be a topological space.
Let $H \subseteq S$ be a subset of $S$.
$x \in H$ is an '''isolated point of $H$''' {{iff}} $x$ is not a limit point of $H$.
That is, {{iff}} $x$ is not in the derived set of $H$.
\end{definition}