In Spanish, azteca as an adjective doesn't seem to inflect for gender, though it does for number: azteca, aztecas. Hence the phrase el rey azteca.

In Italian, azteco seems to be a perfectly regular adjective.

What precedent is there for preferring one or the other of these in Latin? The etymology says that Spanish azteca comes from a Nahuatl suffix -tecatl. Perhaps people then treated the Nahuatl suffix grammatically by analogy with the Latin/Greek suffix -thēca/θήκη. Coming from classical roots, this suffix only forms nouns, like bibliotheca and discotheca, not adjectives, so the analogy is imperfect, but that's often how it is when extending precedents to new cases.

Another reasonable possibility is to reject the analogy as false to begin with, since the Nahuatl suffix means "inhabitant", whereas the Latin suffix means something more like "container for a collection". But it's also reasonable to think of an ethnic group or civilization as a sort of contained collection.

  • 2
    Notably the absolutive plural version of -tecatl is -tecah, which is much more similar to the Spanish form. (I'm also more familiar with the suffix being -catl, with no -te-, as in Mexica < Mēxihcah "Aztecs/Mexicans" < Mēxihco "Tenochtitlan/Mexico City".)
    – Draconis
    Commented Jun 6, 2018 at 0:02
  • -tecatl impels me to suggest aztecatus, though I know of no precedent.
    – Anonym
    Commented Jun 6, 2018 at 3:12
  • 2
    Note that every Spanish adjective ending in -ista (fascista, materialista, etc.) inflects in the same way.
    – brianpck
    Commented Jun 6, 2018 at 12:46

4 Answers 4


While many romanizations of ethnonyms take the 2nd declension noun pattern (Germani, Galli, Veneti, Helvetii and so on), the 1st declension, as Joonas noted, also occurs, although I am struggling to come up with any examples beyond Belgae. 3rd declension is also found, but is rare and seems to always be of pre-classical origin.

However, the main reason I am writing this answer is to stress that the Latin idiomatic way of expressing the “king of X” concept is not to name the land, but rather the people over whom the said king reigns, with the noun for the people taking, naturally, the genitive plural. That is, the pattern is not the “German (Swedish, Belgian, American) king,” but instead “the king of the Germans (Swedes, Belgians, Americans).” There are many examples of this very idiomatic pattern, for example, in Caesar [B. G.]: Ariovistus rex Germanorum [1, 31, 10] (masc., 2nd decl.); Teutomatus, Olloviconis filius, rex Nitiobrogum [7, 31, 5] (masc., 3rd decl.); or in Cicero where he acrimoniously mocks Caesar himself as rex populi Romani [Off. 3, 83], “king of the Roman people;” there are many many others. Incidentally, the modern title of the Belgian king is also the “king of the Belgians” (koning der Belgen, roi des Belges).

So, whichever declension of the word for Aztec people you would pick, the idiomatic Latin is to title the king as “King of the Aztecs,” rex Aztecarum/Aztecorum. Personally I would go with the 2nd declension Aztecus, -i as the most common pattern, but this is really your call. Neither way would be wrong.

  • 1
    Thanks! You've convinced me to fix the name of the restaurant in this question. And now that you point it out, even with my intermediate-level ear for Latin, rex Aztecorum sounds like a much more dignified name for a restaurant than rex Aztecus. I think I was doing something like "hypercorrecting": since Latin so often uses an adjective where Engilsh uses a genitive, I went with the adjective; but the genitive has the precisely right meaning here, enabling distinctions like Cortesius rex hispanicus Aztecorum.
    – Ben Kovitz
    Commented Jun 6, 2018 at 13:55

I don't think -theca is relevant. To me, it seems that Italian azteco and Latin aztecus just represent an analysis where the last "a" in the original Nahuatl word is removed, giving the root aztec-, and then this is treated like the root of a regular first/second adjective, taking the thematic vowel -o- for the stem of the masculine and neuter forms and the thematic vowel -a- for the stem of the feminine forms.

Aztecus is definitely used, but most of the examples I was able to find are in species names, and biological Latin isn't always "correct" from a Classical perspective. Nonetheless, I don't see any strong reason to reject the form aztecus (and the other forms based on the stem azteco-).

It seems that a handful of Latin adjectives did in fact decline, irregularly, as a-stems in the masculine as well as in the feminine: this answer by fvogel cites Forcellini, who mentions ruricola and indigena and says that advena also came to be used this way (and even came to be used as a neuter-gender adjective, apparently).


Your description of the Spanish treatment of "azteca" reminds me of the classical Latin noun Belga, "a Belgian". Belga is masculine, although it looks feminine and follows the first declension. In addition to that noun, there is the perfectly normally behaving adjective Belgicus.

There are similar pairs of nouns and adjectives in English, too, like "Swede" and "Swedish". You can say "Swedish king", but "Swede king" doesn't quite seem to work. This kind of juxtaposition of two nouns works even worse in Latin in my opinion.

It sounds reasonable to treat Azteca just like Belga in Latin — but I would not be opposed to the separate nouns Azteca and Aztecus either. When used together with rex, what you need is not a noun but an adjective. A masculine adjective has to look masculine1, so rex Azteca sounds definitely wrong to me.

What you have to decide is what to take as the adjective for Aztecs. As sumelic mentions, the adjective Aztecus is already in use, so it is definitely a good choice. You could also use Aztecicus if you want; there are plenty of such adjectives in Latin formed with -icus, including Belgicus. I find myself preferring -icus over -us, but that is a personal opinion. Either way, my suggestion is Rex Aztecus/Aztecicus.

I think comparison with -theca is not fruitful here. Instead, I would simply take the stem Aztec- as given. This stem was formed when the Nahuatl word was reanalyzed and conformed to Spanish, and I see no compelling reason to choose otherwise in Latin.

1 In Latin masculine nouns can look feminine or vice versa. Spanish is more flexible in that respect; the adjective "azteca" can be used for either gender in the same form. In Latin this is impossible in the first declension.

  • 1
    Well, we Spanish treat "azteca" as an adjective with no explicit gender. It could be applied indistinctly to a man or a woman. dle.rae.es/?id=4gU3yRZ We can say that Spanish works like Latin in this aspect "masculine nouns can look feminine or vice versa". Notice that when there is a feminine version, it's explicitly mentioned dle.rae.es/?id=5rVKGkX
    – RubioRic
    Commented Jun 6, 2018 at 7:12
  • @RubioRic Thanks! I updated the answer. In Latin an adjective ending in -a can't be used for masculines, so the two languages differ there.
    – Joonas Ilmavirta
    Commented Jun 6, 2018 at 7:27
  • Oh, I've misread your text. I thought where you say "In Latin masculine nouns", you ment "nouns and adjectives". Sorry about that.
    – RubioRic
    Commented Jun 6, 2018 at 7:31
  • @RubioRic Thanks for the confirmation that "azteca" in Spanish is an adjective without a marked gender (and thanks for illustrating them with the links). I was surprised when I saw the sign in front of El Rey Azteca but Wiktionary agreed with it. I'm curious now about why this happened—and why in Spanish but not Latin or other Romance languages. Do you know of other Spanish adjectives, maybe loan words, that also don't mark the gender explicitly?
    – Ben Kovitz
    Commented Jun 6, 2018 at 13:45
  • @BenKovitz You're welcome. Well, I think that probably there are a few of them. "sutil" for example. dle.rae.es/?id=YqUtnyM . Or "inteligente" dle.rae.es/?id=Lr8kWNx Both derived from Latin. We also got "inca" that was taken from America like "azteca"
    – RubioRic
    Commented Jun 6, 2018 at 13:55

Latin, as a general rule, has two different types of words. The first type inflect fully, and for adjectives that means a full set of case, number, and gender forms. The second type don't inflect at all and use the same form for every case (usually these are only foreign names). And as far as I know, every adjective in the language falls into the first category: there's no adjective which doesn't have a full case-number-gender inflection.

So while the noun "Aztec person" might be borrowed as Astecat (undeclined) or Asteca (first declension), the adjective would have to decline in some way. Either Astecus -a -um or Astecicus -a -um would make sense, though I'd go with the first (back-formed from the noun Asteca) to avoid the pattern -ecic- in the middle.

EDIT: Brianpck has pointed out the adjective nēquam "worthless" is, in fact, indeclinable. I stand corrected! But I believe my point is still valid for foreign/borrowed adjectives.

  • A few points: (1) There are a few indeclinable adjectives, like nequam. (2) I think the distinction isn't so much inflected vs. non-inflected as "fully" declined vs. m. sing. = f. sing.
    – brianpck
    Commented Jun 6, 2018 at 13:38
  • @brianpck (1) Good point! Lemme note that. (2) True, I'm just drawing a contrast between how foreign nouns are treated vs foreign adjectives: foreign nouns are sometimes fully uninflected, while foreign adjectives never are afaik.
    – Draconis
    Commented Jun 6, 2018 at 13:39
  • You and Joonas have me pretty well convinced: dropping the gender just isn't done this way in Latin. Here's my current thinking, after reading your and Joonas's answers: If this were a third-declension adjective, it would automatically drop the masculine/feminine distinction, but it's a first-and-second-declension adjective, which has that distinction. IOW, the relevant precedent is the fact that Latin has first-and-second-declension adjectives, not first-declension adjectives. What do you (and @brianpck) think?
    – Ben Kovitz
    Commented Jun 6, 2018 at 13:40
  • @BenKovitz Indeed, it would either be first/second or third, but never just first. (And all the adjectives for foreign peoples I can think of are first/second, mostly formed with -icus, as in Gallicus "Gaulish".)
    – Draconis
    Commented Jun 6, 2018 at 13:42
  • Another adjective that doesn't decline for gender is *vetus*—fodder for another question.
    – Ben Kovitz
    Commented Jun 6, 2018 at 14:25

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