Translation:The soldier cannot fight in October.
I don't know how strict the rule is, or if there is a rule at all. Hungarians can just do it by ear. Whatever sounds natural. And there may be a few words that can go either way. "Október" could be one of these.
"Októberben" - "Októberban".... hmmmm... the second one sounds a bit weird. But I would guess there are people who say it like that.
Another one is "férfi". You only see high vowels, yet you can say both "férfivel" and "férfival". But it may be because "férfi" is a shortened form of "férfiú".
I know Turkish has a much stricter rule for harmonizing. The last vowel counts. But most of their words don't mix the vowels like Hungarian. And they have exceptions, too.
They also have no neutral vowels which can be in front or back words, unlike Hungarian or Finnish.
I think most of the exceptions come from Arabic, and most of the remainder have to do with a palatalised final consonant affecting the endings.
An interesting result is that you have alkolü "alcohol (accusative)" but futbolu "football (accusative)" because alkol is from French and futbol is from English -- and since French L is further forward than English "dark L", only the French-derived word makes the L take front endings.
Yes, this is very interesting about Turkish. I don't think the same phenomenon exists here in Hungarian, that is, the origin of a word does not influence the harmonizing of suffixes. It is just pure harmony, Hungarian is. :)
But there are cases you would think that the harmony is violated. For example, why would you say "akar-nék", instead of "akar-nák". But it turns out those are two different conjugations of the verb, both valid and meaning different things. But there are people who do use the second one in place of the first one, (I dare say incorrectly), because it is more harmonized that way.
That is really interesting, thank you. Only you can notice these things as a learner of the language, because you are trying to follow the rules you learned. It is all too natural to Hungarians, it does not require any thinking.
híd - hídon, híddal
síp - sípon, síppal
szív - szíven, szívvel
hit - hiten, hittel
Looking at these, it may be that the last consonant also has a role. Voiced vs voiceless consonants? But "p" and "v" are both voiceless. I don't know, I give up. :)
To add more to the confusion:
héj - héjjal (peel, as a noun)
kéj - kéjjel (pleasure)
I've heard the theory that Hungarian used to have another vowel sound.
It was a back vowel, so it took back vowel suffixes, but it later merged with the í vowel and is now spelled and pronounced exactly the same -- but those words which used to have this extra back vowel (such as híd) still take back-vowel suffixes.
So you can't tell from looking at the modern-day Hungarian word what kind of vowel harmony it will take (e.g. by looking at the last consonant or something like that); you would have to know the history of the Hungarian language to know where a particular í came from.
(Reminds me a bit of how zwei, drei or weit und breit have the same vowel sound in standard German but different sounds in many dialects, and the only way to know what the word will sound like in such a dialect, if you don't speak it, is to know what the word used to sound like historically, since you can't tell just by looking at the modern-day form.)
That is also very interesting, thanks! Yes, there used to be variations of some vowels. And you can still catch them in the spoken language in some parts of the region. Not in writing though.
Now, on having to know the history of a word, I do feel like I don't need to know any of it, I could just say it as it should be. But then I am not sure I am the right person to decide that. I would have to meet a word like this that I do know know.
But just looking at "híd", I just want to say "híddal", without any regard to its history. It is just how it sounds natural. There may be several other factors at play here...
Yes, as a native speaker, you just know the right forms and would say "híddal" without needing to know history -- just like any English native speaker older than about three will say "house - houses" but "mouse - mice" without having to think about it or know the reason; they wouldn't say "hice" or "mouses".
The reason here (as other posters also point out) is in fact history. The vowel in híd, síp, etc. used to be a different sound, pronounced closer to the centre of the mouth; as such it used to take the suffixes it takes today regularly. But this usage simply stuck.
This is something that has to be learned; but if you come across a word like this you can be fairly certain that it's been used in Hungarian for quite a while, since it has retained its older behaviour.
vvsey gives some good examples: szív follows ‘regular’ harmony, this is because its long vowel always used to be a front vowel (it is still i or ü in related words in other Finno-Ugric languages), so there was never a reason for it to have the other kind of harmony.
The last vowel counts, so in "október" the final "e" has priority over the "o" and "ó", then you get októberben (same for november-ben).
The fact you say "akarnék" instead of "akarnák" for "I would like" is that, for reasons I don't know, the first person of the indefinite conditional is always "nék", there is no "nák" for first person (however the pair "nák/nék" exists for third plural of definite conditional, so "akarnák" is actually "they would like it").