\begin{definition}[Definition:Euclid's Definitions - Book X (III)/1 - First Apotome]
{{EuclidSaid}}
:''Given a rational straight line and an apotome, if the square on the whole be greater than the square on the annex by the square on a straight line commensurable in length with the whole, and the whole be commensurable in length with the rational straight line set out, let the apotome be called a '''first apotome'''.''
{{EuclidDefRef|X (III)|1|First Apotome}}
\end{definition}