\begin{definition}[Definition:Damping Force]
Consider a physical system consisting of a body $B$ passing through a medium $M$.
In order for $B$ to move, it needs to push $M$ out of the way to make room for it.
Hence $M$ exerts a force upon $B$ which opposes the motion of $B$.
This force opposing the motion of $B$ is referred to as a '''damping force'''.
\end{definition}