\begin{definition}[Definition:Deceleration]
'''Deceleration''' is the term used in natural language to mean '''negative acceleration'''.
Thus, while '''acceleration''' is used to mean '''speeding up''', '''deceleration''' is used to mean '''slowing down'''.
As in the applied mathematical context, '''acceleration''' is used to mean '''any''' change in velocity, including a change in direction while moving at a constant speed, the term '''deceleration''' is generally not used in mathematics.
\end{definition}