To convert 33% to a fraction, we start by recognizing that "percent" means "per hundred." Therefore, 33% can be written as:
\[ \frac{33}{100} \]
So, 33% is equivalent to \( \frac{33}{100} \).
Among the options you've provided, "thirty-three over one hundred" correctly represents 33% as \( \frac{33}{100} \).
Thus, the correct answer is:
thirty-three over one hundred.