\begin{definition}[Definition:Incommensurable]
Let $a, b \in \R_{>0}$ be (strictly) positive real numbers.
$a$ and $b$ are '''incommensurable''' {{iff}} $\dfrac a b$ is irrational.
{{EuclidSaid}}
:''{{Definition:Euclid's Definitions - Book X/1 - Commensurable}}''
{{EuclidDefRefNocat|X|1|Commensurable}}
\end{definition}