People generally write it with И, not Й. Example: "Почему один биткоин так дорого стоит?"

link 1

Furthermore, I decided to consult an orthographic (spelling) dictionary, and it confirmed that биткоин indeed has И before Н. I'll try to add link #2 here. Spelling dictonary is a very reputable source!

link 2

So can somebody please explain why биткоин has И before Н, or is it a complete mystery?

For comparison, Tolkien dwarf names (from 'Hobbit') are spelled in English as Oin and Gloin. In Russian they are Ойн и Глойн. No matter what translation I encountered (I have at least two available), they are always spelled with Й.

  • For your info, I've never heard people pronounce it with «и», it's always «й». Jan 16, 2022 at 10:07

3 Answers 3


This is a hotly debated subject which is almost as old as bitcoin itself. It seems that биткоин has been winning for the last few years. That's probably why this is reflected in the 2019 Russian Language Institute dictionary.

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In linguistics, right and wrong is defined by usus. Below are results from Google Ngrams: Google ngrams: биткоин vs биткойн

And below are the results from National Corpus of Russian Language: National Russian Language Corpus: биткоин vs биткойн

I'm not qualified to speculate about the reasons why биткоин wins out. I would just note that the comparison with Tolkien characters is not very helpful since their names are not widely used in any given community of speakers, and most likely results from choices made by the translators and editors of the Russian editions, rather than Russian speakers in general.

  • 4
    My guess why биткоин is winning is because there are no Russian words ending in -ойн. Apart from personal names, the only Russian words ending in -йн have either -a- or -e- before it, but never -o-: only the words комбайн, портвейн, фрейлейн, бассейн, штейн and their derivatives end in -йн. On the other hand, there's a common widely used word воин, with -o-, so instead of creating a brand-new paradigm for -ойн, биткоин picked up the paradigm of воин.
    – Yellow Sky
    Dec 26, 2021 at 2:21
  • @YellowSky for pedantry's sake, война in gen. pl. ends in -ойн, but I see what you mean. The counter-argument would be that there are not many words which end in -о́ин either, in fact во́ин seems to be the only such word (albeit quite frequent).
    – il--ya
    Dec 27, 2021 at 0:57
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    @YellowSky if we look more generally, there are very few words ending in -о́й- followed by consonants so that й does not end the syllable. Койр, войт (бойл, нойз, инво́йс?) and gen. pl. пройм, пойм, обо́йм, сойм, войн, войск, мойр, мойв, пропо́йц, пойл, стойл, устро́йств, расстро́йств, сво́йств, беспоко́йств, геро́йств, изго́йств, кнутобо́йств. On the other hand for -о́ин we have во́ин, по́иск, кано́инг, ферто́инг. It's hard to draw any conclusions, but I personally like more words from the second list, so much easier to pronounce.
    – il--ya
    Dec 27, 2021 at 1:09
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    When I was in middle school, everyone (literally, everyone) in my class thought that Lucas's saga's title was Звёздные воины ("star warriors", not "star wars")
    – Quassnoi
    Dec 27, 2021 at 1:22

Биткоин has the и before the н because the English word "Bitcoin" has the i before the n.

When adopting loanwords, Russian tends to preserve the original spelling as long as it transliterates back from the original alphabet well enough.

It usually takes some effort to break this habit.

We have words like иод, Таиланд, иена, Иокогама, диакон which are pronounced with the й but spelled with the и.

In the past, Russian also used spellings like биллиард "pool", Иом-кипур, иота, диавол etc., even though all of them were pronounced with the й. These words have since changed their spellings, which are now closer to the actual pronunciations: бильярд, Йом-кипур, йота, дьявол.

Russian also used to transliterate foreign names like Disney, Harvey, Halley, Defoe, Crusoe, Boccaccio etc. as Дисней, Гарвей, Галлей, Дефоэ, Крузоэ, Бокаччио. I have a Russian-Italian dictionary published in 1934, whose author criticizes this approach, which hints at the fact that it was still widely used as recently as then.

The word биткоин was probably adopted by a substantial number of speakers independently, and then the majority just transliterated it preserving the original и because it just felt more natural to them.

  • 1
    I understand you, but this article gives OI --> ОЙ. ru.wikipedia.org/wiki/Англо-русская_практическая_транскрипция
    – Alexander
    Dec 25, 2021 at 12:33
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    @Alexander: if only everyone consulted this article before posting to cryptocurrency forums
    – Quassnoi
    Dec 25, 2021 at 13:48
  • 1
    However the original spelling is not preserved in биткойновый and биткойнер. I think it's more subtle that just a habit to transliterate. Й in Russian tends to end the syllables, so when there are more consonants after it, it feels natural to replace it with и and start another syllable instead.
    – il--ya
    Dec 27, 2021 at 1:30

Unlike "ё" which de-facto is totally accepted to be skipped in favour of "e", "й" and "и" by no means that interchangeable in Russian - one can not spell "коиот" instead of "койот".

What you witness here is that instead of having exclusively phonetic transcription, which would have left us with "биткойн" we also have one that just sort of transliterated the word from latin to Russian, substituting "i" with "й".

It's indeed untypical and something new. There's an example of "ио"/"йо" co-existence in words like иод or "иога"/"йога"but I can not recall of any other Russian word where "ои" will be pronounced as "ой".

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