Do first-declension neuter nouns or adjectives have plural forms?

Question

Although almost all first-declension nouns are feminine or masculine, there seem to be a handful of adjectives that belong to the first declension for all genders, and at least one substantive noun, Pascha, that could belong to the first declension while being treated as a neuter noun (see my previous question Was "Pascha" ever used as a neuter first-declension noun?).

The "first-declension neuters" don't seem to inflect exactly the same as feminine or masculine nouns of the first declension. For example, when neuter, Pascha seems to follow the rule that nominative and accusative of neuter nouns are always identical, so we have

Nominativo hoc Pascha, genitivo huius Paschae, dativo huic Paschae, accusativo hoc Pascha, vocativo o Pascha, ablativo ab hoc Pascha

(Donatus graecus a, "De Nomine", lines 53-55, p. 271 in Donati Graeci, by Federica Ciccolella (2008))

This passage from Donatus graecus a says that Pascha has no plural forms ("pluralia non habet"). I know that the genitive plural Pascharum has in fact been used in some texts, so at first I assumed that the absence of plural forms in the Donatus graecus was simply because of semantic reasons (Pascha being a proper noun, it would rarely be necessary to pluralize it).

But now that I think on it further, it actually seems to me that in the nom/acc/voc plural, there is no form that would be unproblematic as a candidate for the plural of a first-declension neuter. Almost without exception, neuter plural nouns end in the suffix -a in the nominative, accusative and vocative case (the only exceptions I know of, mentioned in this mailing list post, are historical duals like duo and ambo, and haec and quae; in haec at least the part after a is derived from a separate suffixed element). So the regular plural of an a-stem neuter Pascha would be expected to be Pascha- + -a, which presumably would yield the form Pascha (identical to the singular). Although homophony between singular and plural forms undoubtably exists for some Latin words, it seems odd to me in this situation, and I feel like there might be a tendency to avoid it.

However, I feel very doubtful that a neuter noun could take the -ae-type plural that is found for feminine and masculine nouns of the first declension.

So I'm now more inclined than I was at first to accept Donatus graecus a's statement that plural forms do not exist for the neuter noun (at least, not in the nominative, accusative or vocative cases). And it seems to me that the same would likely apply to the adjectives that are supposed to have been used in the first declension to modify neuter nouns, like advena (mentioned in an answer by fvogel) and verna (see this passage in Beiträge zur Griechischen und Römischen Literaturgeschichte, Volume 2). It doesn't seem to have been too uncommon for Latin adjectives of one ending to be defective in the neuter nom/acc/voc plural; that is allegedly the case for a number of third-declension adjectives (I mention some relevant references in my question here).

Can anyone confirm or disprove my hypothesis that first-declension neuters were defective in the nominative/accusative/vocative plural? If I'm wrong, how were the plurals formed: with -a or -ae?

Answer 1

I just found that Nouvelle méthode pour apprendre facilement la langue latine, by Claude Lancelot (? et al?), which I quoted in my previous question about Pascha, includes this word in a list of "those nouns which, as grammarians say, are not used in the plural, though we sometimes meet with examples to the contrary" (p. 150, A New Method of Learning with Facility the Latin Tongue, translated from the French by T. Nugent, 1791).

Nugent's translation says

Pascha, is ranked in this number [of nouns found only in the singular] by Aldus and by Verep [I think this is Simon Verep(a)eus/Verrept]. Yet Vossius thinks we may say tria Pascha, or tres Paschas Christus celebravit.

(p. 155; here is a link to the original French passage, p. 180)

I assume tres Paschas would be feminine, rather than masculine, so that part doesn't really teach me anything new (since I already knew that some authors use Pascha as a feminine noun of the first declension). But tria Pascha is evidence that Vossius at least preferred to use a plural form identical to the singular when the word is neuter (and not given the stem Paschat-).

There are neuter plural forms ending in -gena (although I don't know whether they are first or second declension forms)

It's a bit hard for me to figure out the situation with first-declension adjectives because many of them seem to have had alternative second-declension forms used for the masculine and neuter, such as indigenus and alienigenus. Unfortunately, neuter nominative/accusative forms ending in -a are morphologically ambiguous: while they might be the first-declension forms that I speculated could exist in my original post, they might also just be second-declension forms. So the following evidence does not establish the existence of a specifically first-declension neuter plural ending -a for adjectives of this type.

The Latin Lexicon/Numen entry for aliēnigenus, aliēnigena, aliēnigenum mentions two examples of the form aliēnigena being used by Valerius Maximus to modify a neuter plural noun. Here are the relevant sentences as given by the PHI Latin Texts corpus:

• Adici nostris duo eiusdem generis alienigena exempla non absurde possunt.

  (Facta et Dicta Memorabilia 1.5(ext).1.1)

• quas Athenas, quam scholam, quae alienigena studia huic domesticae disciplinae praetulerim?

  (Facta et Dicta Memorabilia 2.1.10.8)