\begin{definition}[Definition:Bounded Class/Bounded Subset of Class]
Let $B$ be a class.
Let $B$ be a subclass of a class $A$.
Then $B$ is a '''bounded subset of $A$''' {{iff}}:
:there exists a set $x \in A$ such that $B$ is '''bounded by $x$''' 
That is, {{iff}} every element of $B$ is a subset of $x$.
\end{definition}