Hapax legomena

So while perusing my dictionary, I found this gem of a word, meaning a word or form that occurs only once in the corpus of a given language.

How in the heck is this word used usefully? Is it only used with dead languages? Or does citing a “hapax legomena” in a living language not contribute to annulling that word’s hapax lemomenal status? Or do you say, “Until so-and-so a date, so-and-so word was a hapax legomena, but then so-and-so author cited it in a famous work and it has entered the popular lexicon since.”

I’ve only seen the term used with regard to linguistic analysis of a given text or body of text, not a whole language. I.e., “elephantine” is a hapax legomena in Trollope’s Palliser novels. (No idea if this is true.) I think it’s generally more interesting to see how many hapax legomena occur in the group of words examined, rather than what exactly the wordsd are, thus using the number of hapax legomena as a measure of the vocabulary’s variety. I think you can also look at the number of hapax legomena and what they are in order to get an idea of the morphological productivity of a prefix, suffix, or whatever. So if I find that “tearability” “lickability” and “spankabliity” are hapax legomena in a 100.000 word corpus from the New York Times, that would tell me that “-ability” is a very productive suffix.

Unfortunately, the book I remember this being discussed in doesn’t have an index. Hopefully somebody who knows more will be around in a few minutes.

I’ve heard it used with regard to an entire language – usually, as the OP suggests, a dead one. There are quite a few hapax legomena in Middle English; sometimes we can figure out what they mean by the context or etymology, but often we’re not really sure.

I don’t think talking about a word counts as a citation, since it doesn’t add to our knowledge about how to use the word, but I’ll defer to the experts on this one.

If you have only one, it’s a hapax legomenon, by the way; legomena is plural.

I’ve only seen the phrase used when talking about words that only appear in the Bible once. Sometimes the meaning may be clear from related words or context, but usually it’s not particularly obvious.