I came across this comment just now:


Which got me thinking.

秘 is still read "bi" in:

  • surnames

  • transcriptions (e.g.: Peru)

Cantonese carries the pronunciation:


Sichuanese also has 秘 as "bei" in certain instances:

秘密 beimi 秘,读“背”。成都人通常称有所隐蔽,不让人知道的话及事情:~档案│~活动。又为“背密”。

Matthews' also has it listed under "bi":

enter image description here

Middle Chinese pronunciations also seem to be way close to "bi" than "mi."

So what gives? Where did "mi" come from?

edit: I'm thinking maybe 秘 sounded like 屄, and it was changed purposely because of taboos. (http://www.sohu.com/a/219931086_413427) "山东方言对女性的某个器官的发音为“比”,因此,为了避免与比字同音,凡是在读笔字时都要读成北,于是,便有了钢北,毛北,圆柱北。"

  • I think someone confused 秘密(bi mi) with 密密(mi mi). the former means "secret " the latter means "secretly"; and for some reason people start reading 秘 as mi too. As the reference stated, it was Beijing dialect read it wrong. Cantonese doesn't have this problem
    – Tang Ho
    Commented Aug 26, 2019 at 5:02
  • 1
    The problem with 秘 sounded like 屄 can be fixed by a tone change, no need to change the pinyin itself
    – Tang Ho
    Commented Aug 26, 2019 at 5:22
  • @TangHo The tones are different to begin with, but sometimes these types of evolution do take place.
    – Mou某
    Commented Aug 26, 2019 at 5:33
  • 3
    Language evolves over time, and usually in a gradual way. Consider that the lip-placement of "m" and "b" is actually the same, lips pressed together in front. It's not hard to imagine how these pronunciations can diverge over time.
    – Marko
    Commented Aug 26, 2019 at 6:53
  • yes, b and m are both labial consonants.
    – dROOOze
    Commented Aug 26, 2019 at 7:14

1 Answer 1


This is probably not the answer you're looking for, but both「秘」and「泌」underwent the same kinds of shifts (b > m) in certain topolects, so I would just treat it as a simple phonological shift within the labial consonant group (rather than something more "exciting"). I do not believe that the comments on it being a "Mandarin thing" are correct.

enter image description here

Although "time" seems like a cop-out, I would point to similar shifts over "time" like

enter image description here

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