What words in any language are so unacceptable that people refer to them only indirectly, like “the N word”?

The question is not being answered to date by other respondents: are there words in other languages which are not only taboo to use, but even taboo to cite, so that speakers resort to circumlocutions like “N-word” or “F-word”.

Taboo used to be pretty comprehensive: if the word was taboo to use, it was also taboo to even cite. Circumlocutions like this have a history in English (bloody used to be referred like that back in the day), but I don’t think they are widespread. I certainly can’t think of parallels in Greek.

EDIT: Thank you, Robert Neumann: три буквы (“the word with 3 letters”), Russian Хуй, https://www.quora.com/What-words…