Numerator vs. denominator vs. nominator

Solution 1:

The numerator is the top part of a fraction, the denominator is the bottom part, and nominator is not an appropriate term for any part of a fraction.

I have seen nominator used to mean both "numerator" and "denominator". According to a question on this at English.stackexchange, this use of "nominator" is exceedingly rare.

Rather than people having been taught that "nominator" was appropriate, I think that it is far more often the case that the use of "nominator" is an eggcorn that has arisen due to its resemblance to the other two words.

I think using "nominator" should be discouraged because it already has a wholly different meaning, and has no etymological connection to fractions to speak of. It is also helps to confuse the meanings of the proper terms, if it is mixed with them.