Some nouns have multiple plurals, this article from Merriam Webster names a few. I'm wondering if there is a word to describe this, a word meaning having multiple plural forms. To put it in a sentence (two sentences to allow noun and adjective answers):
Syllabus is a(n) (insert word), because it has two plural forms.
Syllabus is (insert word), because it has two plural forms.
I have scanned through the Wikipedia page on English plurals which has a lot of terms for different plural forms, however, I have not come across a term for words with multiple plural forms. I've also scanned through some blogs on the Oxford Dictionaries website, but to no avail.
Some of the examples from the aforementioned Merriam Webster article:
One referendum, multiple referendums or referenda 1
One syllabus, multiple syllabuses or syllabi 1
One gymnasium, multiple gymnasiums or gymnasia 1
One referendum, multiple referendums or referenda 1
One miasma, multiple miasmas, miasmata or miasms 1
One terminal, multiple terminuses or termini 1