\begin{definition}[Definition:Euclid's Definitions - Book I/22 - Quadrilaterals]
{{EuclidSaid}}
:''Of quadrilateral figures, a '''square''' is that which is both equilateral and right-angled; an '''oblong''' that which is right-angled but not equilateral; a '''rhombus''' that which is equilateral but not right-angled; and a '''rhomboid''' that which has its opposite sides equal to one another but is neither equilateral nor right-angled. And let quadrilaterals other than these be called '''trapezia'''.''
{{EuclidDefRef|I|22|Quadrilaterals}}
\end{definition}