I have found the following sentence:

Девочка сидит на мосту.

However, when I looked up мост in my dictionary, I found that it listed two declined forms on the prepositional, which is мосте and мосту.

For my tiny knowledge of Russian, you usually add е to the end of the masculine word for a prepositional form.

So why does it use мосту? And how can you differentiate two forms?

  • "На мосту" is a locative case. There are several topics on subject already. E.g. russian.stackexchange.com/questions/9284/…
    – Matt
    Aug 27, 2015 at 7:16
  • 1
    @user4419802 Thanks but I cannot get what they are talking about. It seems that I broke into a somewhat advanced topic for my current understanding...
    – Blaszard
    Aug 27, 2015 at 7:34

2 Answers 2


Well, the problem as usual goes deep into the history of the language. I try to recollect as much as I remember, and if I fail let's other will improve my story. So let's begin in the beginning.

Once Russian nouns had 4 types of declension, but nowadays there are only 3 remaining. As the consequence of this shift some nouns got 2 forms of prepositional case - a new one along with an older one. BTW. Prepositional case is the new acquisition in Russian language too. In the old times there was Locative case which was (almost) fully absorbed by newcomer Prepositional.

The biggest part of nouns has now no trace of old Locative. Say, "Я в деле" (I'm in) and "Поговорим о деле" (Let's talk about business) - both are the very same case. But some nouns got two forms which are now used differently (as the old joke says, there's no use of having many clocks if they all show the same time). So consider, "Я в лесу" (I'm in the forest) vs "Что мы знаем об этом лесе?" (What do we know about this forest?). Different forms, different meanings.

How to treat this situation, whether it's a brand new locative case or the special second form of prepositional case, is the matter of agreement. Anyway, one has to know and use it properly. In example sentence, "Девочка сидит на мосту" the bridge surely is a location of a girl, so one should say "на мосту" not "на мосте".

  • Thanks. But I still can't get what is the difference between "на мосте" and "на мосту". If I say "Девочка сидит на мосте.", does it just convey a different meaning from на мосту or is it not even the proper sentence and doesn't make sense grammatically in the first place?
    – Blaszard
    Aug 27, 2015 at 21:37
  • 1
    @Blaszard Usually when talking about some kind of "location" locative case is preferred. Yet it really depends upon the word. I say, "Сидит на мосту" is strongly preferred over "Сидит на мосте". But I don't think the same thing about e.g. "Стоит на мысе" vs "Стоит на мысу".
    – Matt
    Aug 27, 2015 at 21:56
  • A general rule for these -у 'locatives' is to use -у when expressing location; use -е for other prepositions that take the prepositional case. So: Депутаты Петербурга снова решили не обсуждать вопрос о мосте "St. Petersburg deputies decided again not to discuss the question about the bridge"; Мы стояли на мосту "We stood on the bridge." Similarly: Стихи о лесе "poems about the forest"; Они были в лесу "They were in the forest."
    – Curt
    Sep 3, 2016 at 21:17

Склонения слова Мост: http://udarenieru.ru/index.php?doc=%D0%BC%D0%BE%D1%81%D1%82

  • Дательный: Мосту
  • Предложный: Мосте
  • Предложный 2: Мосту

У слова 2 варианта написания в предложной падеже.


Златая цепь на дУбе том

  • Неужели кто-то серьёзно говорит "стук в заднем мосте"?! "Стук в заднем мосту" конечно же. Дело не в предлогах "в" или "на", а в физическом местоположении. И "едут по мосту" - это вообще-то дательный падеж.
    – Matt
    Aug 27, 2015 at 16:52
  • Скажут, всё-таки, наверное, "задний мост стучит". Aug 27, 2015 at 17:01
  • Стук в заднем мосте (мостах) - Предложный. (Иначе было бы в обоих мостам).
    – zerg
    Aug 27, 2015 at 17:06
  • Автомобили едут не почему а по чём. По мосту (По чём?). По воде не проедут (Почему?).
    – zerg
    Aug 27, 2015 at 17:13
  • Убрал привязку к контексту. Но с местом я тоже не согласен.
    – zerg
    Aug 27, 2015 at 18:51

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