Definition:Square Root

Square roots of primes
From Square Root of Prime is Irrational, no prime number can be expressed precisely by a rational fraction.

The decimal expansions of the first few primes are as follows:

Also known as
Because square roots (and in particular, positive square roots) are so much more commonly encountered in mathematics than any other sort of root, $\sqrt x$ is frequently just called root $x$

In translations of Euclid's, the word side can be found, often in quotes to emphasise the awkward nature of the language available to the Ancient Greeks.