Definition:Square Root

Definition
A square root of a number $n$ is a number $z$ such that $z$ squared equals $n$.

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 square roots 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, the word side can be found, often in quotes to emphasise the awkward nature of the language available to the Ancient Greeks.

Historical Note
It is suggested by some sources that the symbol $\surd$ (a stylised r for radix) for the square root may have originated with, but there is evidence that it may have been around a lot earlier than that.