I am not natively English speaking and I was wondering about this spelling when I saw the title of the movie "The Martian".

This pattern also seems to apply to other things ending on an "s" sound, like

  • Venus -> Venutian (though it's less common than Venusian)
  • Venice -> Venetian

On the other hand, there is examples showing the exact opposite, like

  • Paris -> Parisian
  • France -> French
  • Los Angeles -> Angeleno (probably derived from its hispanic origin)

Why is it not "Marsian" and "Venecian" like it is in German for instance ("Marsianer", "Venezianer")?

Is there a rule for how demonyms are spelled or do they evolve historically?

  • 1
    Have you tried to research this question yourself? Google has quite a lot of information on the historical origins of words.
    – mikeagg
    Commented Dec 8, 2015 at 14:03
  • 1
    Because "Marshians" are people from the Black Lagoon.
    – Hot Licks
    Commented Dec 8, 2015 at 14:19
  • Your question is a little unclear. Are you asking about how demonyms are derived, or are you asking about how their spellings are derived? There are no rules about either; there are certain patterns, but there are exceptions to every pattern.
    – choster
    Commented Dec 8, 2015 at 15:30
  • @mikeagg, I've researched myself a bit, but it's hard to formulate such a question to a search engine like Google, because the longer the search term, the more unrelated results you get.
    – Stacky
    Commented Dec 8, 2015 at 18:00
  • 2
    'Venusian' is actually more common than 'Venutian' Commented Dec 8, 2015 at 18:27

3 Answers 3


There is no general rule about this kind of alternate word stem used when forming demonyms. Each pair you list has a different history that explains the form used. The different stems or suffixes used in the words for the place and the inhabitant are usually the result of historical evolution in other languages, so the rules are different depending on the source language and the time the word entered English. (For example, as AP mentioned, the t in martian is taken from Latin forms of words relating to Mars. Angeleno appears to be derived from Spanish angeleño with the ñ converted to an n. French is derived from a fusion of a root meaning France plus a native English suffix that has a completely different etymology from -ian.)


Martian is defined by AHD as:

  1. Of or relating to the planet Mars or its hypothetical inhabitants.

  2. A hypothetical inhabitant of the planet Mars, especially as a stock fictional character.

[Middle English marcien, from Latin Mārtius, from Mārs, Mārt-, Mars.]

According to this Latin-English dictionary entry, Martius means "of or belonging to Mars".

Given the above, it's easy to see where the "t" in the English word Martian comes from.

Regarding e.g. Venutian, my offline Webster's Unabridged has this to say:

see Venusian

Etymology: Venus, 2d planet from the sun + English -tian (as in Martian)

As pointed out in the comments above, venusian is much more common than venutian.

  • OK, it's derived from the latin "Matius", but that doesn't answer the quesion. I could ask the same question for the word pair "Mars" and "Martius".
    – Stacky
    Commented Dec 8, 2015 at 14:55
  • 2
    @Stacky I assume you're asking about English words. There is no English pair of "Mars" and "Martius". "Martius" is a Latin word, and this is where the "t" in "Martian" comes from (which was your question, if I read it right). "Mars" also comes directly from Latin, unchanged.
    – A.P.
    Commented Dec 8, 2015 at 17:38
  • Probably I'm being unprecise, but I am actually asking, why "Martius" or "Martian" is written with a "t" while "Mars" is written with an "s". Why is it not "Marsius" resp. "Marsian" like it is in other languages?
    – Stacky
    Commented Dec 8, 2015 at 18:11
  • 1
    OK, the English "Martian" comes from the Latin "martius". Hence the "t". Why the Latin word has a "t" I'm not sure, but questions about Latin are off-topic here. I'm no Latin expert, but let me guesstimate that the adjective "martius" has a "t" because it's derived from "Mars". "Mars" is a third declension noun whose genitive is Martis (note the "t").
    – A.P.
    Commented Dec 8, 2015 at 18:37
  • The "t" is part of the Latin root for "Mars." As roguemue says in his answer, the "t" was lost in the nominative form before the ending -s, but preserved in other parts of the paradigm. (You can also see this sound-change in the nominative forms of adjectives like importans in Latin, which corresponds to the English word important).
    – herisson
    Commented Dec 8, 2015 at 19:07

The name of the Roman war god is Mars, nominative, and Martis, genitive. Latin nouns with the genitive ending -is often show shortening of the nominative. I assume, the nominative originally also had the ending -is. By shortening the nominative one got two different forms which is much more practical.

So the normal stem of the word is Mart- and in Mars we have a changed stem Mar with drop of t (Martis > Mart•s > Mar••s).

Latin adjectives eg in -anus or -ianus are formed from the full stem and not from the shortened stem.

  • There's no need to assume the nominative originally had the ending -is. We have some records of Old Latin, and we also have the ability to reconstruct the original forms of some endings based on comparison with other languages. So you should cite some source that describes what the actual historical forms are.
    – herisson
    Commented Dec 8, 2015 at 17:57
  • According to Wikipedia, for Latin consonant-stem nouns of the third declension, the genitive ending -is actually descends from earlier -es. There is no evidence I can find that the nominative ending for these nouns was ever -is: this does not seem to be true in Old Latin, Proto-Italic, or Proto-Indo-European.
    – herisson
    Commented Dec 8, 2015 at 18:41

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