\begin{definition}[Definition:Porism]
The '''porism''' is a term whose precise definition is difficult to pin down.
It arises from the works of {{AuthorRef|Euclid}}, and appears to have two different meanings:
# A result which follows directly, or in passing, during the course of proving something else; that is, a corollary.
# A proposition that asserts that there may be conditions under which a particular problem has either no solutions or an indeterminate number of them.
\end{definition}