\begin{definition}[Definition:Relatively Closed Set/Definition 2]
Let $T = \left({S, \tau}\right)$ be a topological space.
Let $A \subseteq B \subseteq S$.
'''$A$ is relatively closed in $B$''' {{iff}} there is a closed set $C \subseteq S$ with $C \cap B = A$.
\end{definition}