\begin{definition}[Definition:Base of Geometric Figure]
The '''base''' of a geometric figure is a specific part of that figure which is distinguished from the remainder of that figure and placed (actually or figuratively) at the '''bottom''' of a depiction or visualisation.
In some cases the '''base''' is truly qualitiatively different from the rest of the figure.
In other cases the '''base''' is selected arbitrarily as one of several parts of the figure which may equally well be so chosen.
\end{definition}