\begin{definition}[Definition:Euclid's Definitions - Book X (III)/4 - Fourth Apotome]
{{EuclidSaid}}
:''Again, if the square on the whole be greater than the square on the annex by the square on a straight line incommensurable with the whole, then, if the whole be commensurable in length with the rational straight line set out, let the apotome be called a '''fourth apotome''';''
{{EuclidDefRef|X (III)|4|Fourth Apotome}}
\end{definition}