I looked in a couple of dictionaries, and they claim that комплексный is stressed on o - кóмплексный. However, when it comes to complex numbers in math, most of the professors at my university (many of whom are Russian in fact) stress е - комплéкснoe число. Is this pronunciation correct? Is it specific to math?

  • For years I've listened to that person on TV saying кухóнный. University professor are even more strange. One of my professors would say врéменный instead of временнóй and vice versa.
    – GSerg
    Jun 16, 2012 at 13:50
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    @GSerg If it also happened vice versa then he just didn't which word meant what, I think :). Jun 16, 2012 at 17:41
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    The term should of course be комплéксное число, not комплéксный число as is currently written in the question. In any case, the stress in комплéкснoe is definitely specific to math about complex numbers or related themes (e.g., an almost complex structure on a manifold is почти комплéксная структура). Be careful not to use this adjective to refer to something that is complex in the sense of being complicated, which would be translated as сложный. And in fact сложный itself has an additional mathematical meaning: сложная функция is not "complicated function" but "composite function".
    – KCd
    Jun 17, 2012 at 3:40
  • Concerning my previous comment, the reason сложный means "composite" for functions is that it comes from сложение, which means "compounding", as in a process of more than one part. Thus сложение means addition (the simplest compound process in math) and сложная функция means a composite (= compounded) function.
    – KCd
    Jun 17, 2012 at 3:45

3 Answers 3


My knowledge, stemming from my math professor in university and supported by Lopatin dictionary, is that it's комплeксный in math (complex numbers) and комплексный otherwise.

Taking into account that it's always complex in English, I wonder where this distinction comes from.

The Wikipedia article about complex numbers suggests that both options are possible and provides the following note:

Двойное ударение указано согласно следующим источникам.

  1. Большая советская энциклопедия, 3-е изд. (1973), том 12, стр. 588, статья Ко́мпле́ксные числа.
  2. Советский энциклопедический словарь (1982), стр. 613, статья Ко́мпле́ксное число.
  3. Последнее издание «Словаря трудностей русского языка» (Розенталь Д. Э., Теленкова М. А., Айрис-пресс, 2005, стр. 273) указывает оба варианта: «ко́мплексные (компле́ксные) числа».
  4. В Большой российской энциклопедии (том 14, 2010 год) по необъяснённым причинам предлагаются одновременно ударения Компле́ксное число (стр. 691), но Ко́мплексный анализ (стр. 695).

В следующих источниках указан единственный вариант ударения (на второй слог) для чисел:

  1. Орфографический словарь русского языка (6-е издание, 2010),
  2. Грамматический словарь русского языка (6-е издание, 2009),
  3. Русский орфографический словарь Российской академии наук под ред. В. В. Лопатина (2-е издание, 2004).
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    Why is it always complex in English..? It's actually one of the classic examples where the stress determines the part of speech. It's always complex in nouns and complex in adjectives. Jun 16, 2012 at 17:37
  • @VitalyMijiritsky Interesting! This page thefreedictionary.com/complex gives too parallel definitions. According to one, there is a double stress possible (which I didn't know). According to the second one, the stress is always on the first syllable.
    – texnic
    Jun 16, 2012 at 20:39
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    it depends on the part of speech. The same is with the word permit. It's pErmit for nouns and permIt for verbs. Jun 16, 2012 at 20:54
  • You mention the stress in the English word, but the word is more likely to be borrowed from German or French. In French the stress is, as always, on the last syllable, not sure about German. May 20, 2016 at 20:02

I'd say that компле́ксный with the stress on e is a trait of certain professional slang, in this case, the math one.

On every other occasion this word its regular stress, кóмплексный.

Different stress as a feature of professional slang is not at all uncommon in Russian. A construction worker, for example, would refer to a number of cranes as краны́, the regular stress being кра́ны. An IT guy might say драйвера́, the more regular form being дра́йверы.


As far as I know it depends on a university and a geographical region, somewhere it's pronounced комплéксное and somewhere кóмплексное. Both are correct in colloquial speech as it's a professional term.

  • What are some geographic regions where complex number = кóмплексное число? I once attended a lecture where a mathematician educated in St. Petersburg pronounced нормирование (valuation) with the stress on the a, and students from the Moscow area told me they thought that sounded funny because to them the stress is on the (first) и.
    – KCd
    Jun 17, 2012 at 3:50
  • I studied in Moscow and both in school and institute it was кóмплексное число. I do not remember ever hearing the word with a stress on e.
    – Anixx
    Jul 6, 2012 at 12:22
  • @Anixx In Saint Petersburg it seems to be common to pronounce it as комплéксное (university and school too). So your comment perfectly confirms my theory about geographical differences.
    – iHunter
    Jul 6, 2012 at 12:38
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    @iHunter, technically, it does not confirm your theory, but conforms to your hypothesis.
    – theUg
    Feb 2, 2013 at 17:57

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