\begin{definition}[Definition:Euclid's Definitions - Book I/17 - Diameter of Circle]
{{EuclidSaid}}
:''A '''diameter of the circle''' is any straight line drawn through the center and terminated in both directions by the circumference of the circle, and such a straight line also bisects the center.''
{{EuclidDefRef|I|17|Diameter of Circle}}
\end{definition}