Huh. Merriam-Webster doesn't have an entry for "elven."
"Elfin"? Yes. "Elvish"? Yes. But not "Elven."
Other dictionaries include "elven," which makes me wonder what M-W is waiting for. Is it not used enough outside of fantasy novels?
This sends me to Google Ngrams... and now I want to explore how "elven" was used in various works—and when those works became particularly popular.
But no. I have responsibilities.
@Alexis_WordsUnbound Two, count 'em TWO different spell checkers rejected "hissy". Naturally I threw a fit.