\begin{definition}[Definition:Euclid's Definitions - Book XI/14 - Sphere]
{{EuclidSaid}}
:''When, the diameter of a semicircle remaining fixed, the semicircle is carried round and restored again to the same position from which it began to be moved, the figure so comprehended is a '''sphere'''.''
{{EuclidDefRef|XI|14|Sphere}}
\end{definition}