What is appropriate usage of "numerator", "denominator", and "nominator" to refer to parts of a fraction?
I'm posting this question and answer here because I had little luck finding a clear answer through Google. I realize that it's not really mathematics, but I think it's worth mentioning as an educational issue.
Ideally, the question at English.stackexchange would address this completely, however they have closed it with the reason: "you can just look it up". I agree that this is possible, but I don't think that reveals the consensus. I wanted to allow for more opinions to be expressed. (Below, I argue that "nominator" should be discouraged.)
Best Answer
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.