\begin{definition}[Definition:Ratio]
Let $x$ and $y$ be quantities which have the same dimensions.
Let $\dfrac x y = \dfrac a b$ for two numbers $a$ and $b$.
Then the '''ratio of $x$ to $y$''' is defined as:
:$x : y = a : b$
It explicitly specifies how many times the first number contains the second.
{{EuclidSaid}}
:''{{:Definition:Euclid's Definitions - Book V/3 - Ratio}}''
{{EuclidDefRefNocat|V|3|Ratio}}
\end{definition}