[nonbirithm]

Or how Siri means "buttocks" in Japanese?

[jki275]

It’s oshiri, not Siri.

[nonbirithm]

Actually the 'o' is a modifier for politeness. It seems there's a version of the word without an 'o'.

https://jisho.org/search/shiri

[jki275]

I'm aware... But the word isn't pronounced the same anyway, and I've never heard it used without the o either.