propreantepenultimate

As a noun terms

is .

As an adjective propreantepenultimate is

(rare) of, on, to, or that is the last (l) but four / fifth syllable from last (of a (l) or other (l)).

In lang=en terms the difference between propreantepenultimate and propenultimate

is that propreantepenultimate is of, on, pertaining to, or that is the last syllable but four / fifth syllable from last (of a word or other utterance) while propenultimate is two before the last, an alternative to antepenultimate.