Why does gemination happen in many 真 compounds?


Inspired by <https://japanese.stackexchange.com/a/38733/3295>

Some examples [from
Wiktionary](https://en.wiktionary.org/wiki/%E7%9C%9F#Readings):

> 真っ暗 (makkura, "total darkness")  
>  真っ向 (makkō, "directly opposite", "right in front")  
>  真っ黒 (makkuro, "pitch black)  
>  真っ最中 (massaichū, "infull swing, in the midst")  
>  真っ青 (massao, "deep blue")  
>  真っ赤 (makka, "bright red")  
>  真っ先  
>  真っ直ぐ  
>  真っ二つ  
>  真っ白

Also possibly related: `真ん丸`, `真ん中`.

The usual rules for gemination don't seem to apply: `真{ま}` doesn't end in `つ`
or `く`, so where does っ come from?

[@user4092](https://japanese.stackexchange.com/users/4092/user4092) puts
forward this theory in a comment:

> As for 真っ白, some claim that it derives from prefix "ma" with reduplicated
> adjectives, which is shared with Filipino or Melanesian languages. This
> feature is well reserved in "ma aka aka" → まっかっか.

To be honest I'm somewhat skeptical of this.

For now my pet theory is that it's related to the reading まこと, but is there a
commonly accepted explanation?




(Seems like we're not getting anything more specific, so I'll format my
comments as an answer for ease of future reference.)

The electronic edition of the _Kokugo Dajiten_ has it like this:

> 接頭語「ま」の下に促音の挿入された形,

So the standard view isn't that it was _makoto_ > _maQ-_ ; but rather a simple
_ma-_ , to which _-Q-_ was later tacked on. And indeed, of the words you've
cited, most of them have non-geminated attestation in historical documents;
though that, in itself, isn't decisive, since gemination wasn't always written
down consistently. Still, I think the standard analysis is more likely true
than not.

Why? If you consider some prefixes ending with _-ki/-ku_ that create
gemination, you'll find these are often _on’yomi_ , i.e. Chinese loans, like
悪- _aku-_ in 悪口 _akkō, akku_ or 石 _seki-_ in 石鹸 _sekken_. But these trace
straightforwardly to Middle Chinese readings ending in consonants, such as *
_ʔak_ and * _dźak_ in this example (compare the modern Cantonese readings:
_ok_ , _sek_ ). We know these loans retained their final consonants even in
Japanese for a good while. It's natural that a syllable-final consonant would
coalesce into a geminated one

What that has to do with anything? Well, _ma-_ is a native Japanese prefix,
seen in the 8th-century _Man'yōshū_ in expressions like _ma-kanasimi_ "truly
sad", or 旅とへど真旅になりぬ "I said I'd set out on a [little] journey, but—lo and
behold!—now it has become a real [long] one." Linguists have many reasons to
believe that Old Japanese had no gemination, so _ma-_ was a perfectly
cromulent prefix by itself, predating the introduction of geminated consonants
into the language. In fact, it's very likely that _makoto_ itself is just
_ma+koto_ 真事/真言, true things/true words (again as per _Daijiten_ ).

Since we had a native Japanese _ma-_ rather than a Chinese _mak-_ , there
seems to be no reason for it to trigger gemination. True, the Japanese _onbin_
changes also triggered gemination, like _torite_ → _totte_ ; but not with [k],
since the _onbin_ form of _kakite_ resulted in _kaite_ instead. Then whence
the _-Q-_ in _maQ-_? Consider that both historically and synchronically, _Q_
is added to create emphasis:

  * _matashi_ , _mataku_ (historical form) → _mattaku_ (modern form) 
    * → まっっったく (tongue-in-cheek superemphasis in manga or the Internet, etc.)
  * _yohodo_ → _yoppodo_ (both forms still coexist)
  * _mina_ → _minna_ (also works with nasals)

Consider also that there are several other emphatic prefixes with a _-Q-_ (取っ,
引っ, 打っ, 押っ as in 押っ死ぬ、押っ放り出す…), and also the use of _Q_ in interjections like
"こわっ!"

Given the meaning of 真 as "true, truly, for real", it makes sense for it to
receive emphatic gemination, which in time lexicalized into forms like 真っ黒,
etc. We can predict from this that, if a word has a 真 prefix but didn't get an
emphatic っ fossilized into its lexical entry, it could still get a っ for extra
discursive emphasis; and in fact, forms like
[まっこと](https://twitter.com/search?f=tweets&vertical=default&q=%22%E3%81%BE%E3%81%A3%E3%81%93%E3%81%A8%22&src=typd)
or
[真ん夏](https://twitter.com/search?q=%22%E7%9C%9F%E3%82%93%E5%A4%8F%22&src=typd)
are easy enough to find online.




(Seems like we're not getting anything more specific, so I'll format my
comments as an answer for ease of future reference.)

The electronic edition of the _Kokugo Dajiten_ has it like this:

> 接頭語「ま」の下に促音の挿入された形,

So the standard view isn't that it was _makoto_ > _maQ-_ ; but rather a simple
_ma-_ , to which _-Q-_ was later tacked on. And indeed, of the words you've
cited, most of them have non-geminated attestation in historical documents;
though that, in itself, isn't decisive, since gemination wasn't always written
down consistently. Still, I think the standard analysis is more likely true
than not.

Why? If you consider some prefixes ending with _-ki/-ku_ that create
gemination, you'll find these are often _on’yomi_ , i.e. Chinese loans, like
悪- _aku-_ in 悪口 _akkō, akku_ or 石 _seki-_ in 石鹸 _sekken_. But these trace
straightforwardly to Middle Chinese readings ending in consonants, such as *
_ʔak_ and * _dźak_ in this example (compare the modern Cantonese readings:
_ok_ , _sek_ ). We know these loans retained their final consonants even in
Japanese for a good while. It's natural that a syllable-final consonant would
coalesce into a geminated one

What that has to do with anything? Well, _ma-_ is a native Japanese prefix,
seen in the 8th-century _Man'yōshū_ in expressions like _ma-kanasimi_ "truly
sad", or 旅とへど真旅になりぬ "I said I'd set out on a [little] journey, but—lo and
behold!—now it has become a real [long] one." Linguists have many reasons to
believe that Old Japanese had no gemination, so _ma-_ was a perfectly
cromulent prefix by itself, predating the introduction of geminated consonants
into the language. In fact, it's very likely that _makoto_ itself is just
_ma+koto_ 真事/真言, true things/true words (again as per _Daijiten_ ).

Since we had a native Japanese _ma-_ rather than a Chinese _mak-_ , there
seems to be no reason for it to trigger gemination. True, the Japanese _onbin_
changes also triggered gemination, like _torite_ → _totte_ ; but not with [k],
since the _onbin_ form of _kakite_ resulted in _kaite_ instead. Then whence
the _-Q-_ in _maQ-_? Consider that both historically and synchronically, _Q_
is added to create emphasis:

  * _matashi_ , _mataku_ (historical form) → _mattaku_ (modern form) 
    * → まっっったく (tongue-in-cheek superemphasis in manga or the Internet, etc.)
  * _yohodo_ → _yoppodo_ (both forms still coexist)
  * _mina_ → _minna_ (also works with nasals)

Consider also that there are several other emphatic prefixes with a _-Q-_ (取っ,
引っ, 打っ, 押っ as in 押っ死ぬ、押っ放り出す…), and also the use of _Q_ in interjections like
"こわっ!"

Given the meaning of 真 as "true, truly, for real", it makes sense for it to
receive emphatic gemination, which in time lexicalized into forms like 真っ黒,
etc. We can predict from this that, if a word has a 真 prefix but didn't get an
emphatic っ fossilized into its lexical entry, it could still get a っ for extra
discursive emphasis; and in fact, forms like
[まっこと](https://twitter.com/search?f=tweets&vertical=default&q=%22%E3%81%BE%E3%81%A3%E3%81%93%E3%81%A8%22&src=typd)
or
[真ん夏](https://twitter.com/search?q=%22%E7%9C%9F%E3%82%93%E5%A4%8F%22&src=typd)
are easy enough to find online.

