A (straight line) commensurable in length with a binomial (straight line) is itself also binomial, and the same in order. * Let $AB$ be a binomial (straight line), and let $CD$ be commensurable in length with $AB$. * I say that $CD$ is a binomial (straight line), and (is) the same in order1 as $AB$.
(not yet contributed)
Euclid's expression "(not) being the same in order" means that the resulting irrational number is "(not) of the same kind" as that irrational number, with which it is commensurable. ↩