\begin{definition}[Definition:Binomial (Euclidean)]
Let $a$ and $b$ be two (strictly) positive real numbers such that:
: $(1): \quad \dfrac a b \notin \Q$
: $(2): \quad \left({\dfrac a b}\right)^2 \in \Q$
where $\Q$ denotes the set of rational numbers.
Then $a + b$ is a '''binomial'''.
{{:Euclid:Proposition/X/36}}
\end{definition}