Answer
Not a monomial (the variable has a negative exponent).
Work Step by Step
A monomial is an expression of the form $ax^{k}$,
where $x$ is the variable,
the exponent $k$, a nonnegative integer, is the degree,
and a is the coefficient of teh term.
Here, we have:
$\displaystyle \frac{8}{x}=8x^{-1}$,
so $k$ is negative, and the expression is not a monomial.
