Romaji for long vowel: 通り vs 東リ


I was told that in romaji the long vowel of o would be ō (see this
[tutorial](http://japanese-lesson.com/characters/romaji/index.html))

However, I am confused by these two words. In Google Translate they both were
romanized as Tōri (see
[here](https://translate.google.com/?sl=ja&tl=en&text=%E9%80%9A%E3%82%8A%0A%E6%9D%B1%E3%83%AA%0A%0A&op=translate)),
but their 平仮名 are different

  * 通り とおり
  * 東リ とうり




Responding to the extended discussion in the comments --

## Terminology

The second vowel is //o// in both 通【とお】り and 東【とう】. (東【とう】り is not a word, so
I won't repeat that here.) When you're talking about vowels, you're talking
about pronunciation. The second **kana** is either お or う, but in both 通【とお】り
or 東【とう】, the **vowel** is //o//.

## Kana spellings

This gets really involved. Hop to the bottom if the details don't matter to
you.

The kana spelling difference is due to different origins -- historically, 通り
came from older とほり. Medial (mid-word) //h//'s often
[lenited](https://en.wikipedia.org/wiki/Lenition) (softened) and disappeared
in many words, leaving behind the vowels. The pronunciation shifted before the
kana spelling did -- the とほり kana spelling was the "correct" spelling up
through the spelling reforms of the mid-20th century.

This older [historical kana
spelling](https://en.wikipedia.org/wiki/Historical_kana_orthography) is still
included in many monolingual Japanese dictionaries, since modern readers are
still likely to encounter this. For instance, see [the 通り entry at
Kotobank](https://kotobank.jp/word/%E9%80%9A%E3%82%8A-581994). At the top of
the page, you'll see kana spellings listed like `とおり〔とほり〕`. The kana string
〔in brackets〕 is the historical spelling.

### Historical spellings for native Japanese terms -- _kun'yomi_

If you spend some time with a monolingual Japanese dictionary that includes
these, you'll notice that many entries for _kun'yomi_ terms with vowel-vowel
combinations like //oo// or //au// come from older historical spellings with
an //h// or //f// in between.

All of the modern //h// or //f// kana, はひふへほ, were probably originally
pronounced with an initial //p//, as //pa pi pu pe po//. These lenited over
time to become first the bilabial fricative //ɸ//, kinda like an "f". We know
that these "f" pronunciations at the beginnings of words were still current in
1603, when the Japanese-to-Portuguese dictionary [the _Nippo
Jisho_](https://en.wikipedia.org/wiki/Nippo_Jisho) was published. We can see
this in the scanned copy over at Google Books, in entries like [on this page
for `F ANTES DO
I`](https://books.google.com/books?id=TFJAAQAAMAAJ&pg=PA87-IA1#v=onepage&q&f=false)
("F before I"), with entries like:

> **Fi**. _Sol_. ( **Fi**. Sun.)

Meanwhile, in a medial (mid-word) position, these pronunciations lenited
further to often become a //w// sound. We see that in places like the word 川,
modern かわ and historical かは. The _Nippo Jisho_ entry
[here](https://books.google.com/books?id=TFJAAQAAMAAJ&pg=PA43-IA1#v=onepage&q&f=false)
(right-hand column, sixth from the top) shows:

> **Caua**. _Rio, ou ribeira._ ( **Kawa**. River, or stream.)

In pretty much all cases except before //a//, this //w// sound basically
disappeared -- so Old Japanese //opo// ("big; many", the root of modern
大【おお】きい or the prefix 大【おお】) became early Middle Japanese //ofo//, then maybe
mid-Middle Japanese //owo//, and then recorded late Middle Japanese //oː//.

### Historical spellings for Chinese borrowings -- _on'yomi_

Entries for _on'yomi_ terms generally don't have this, and instead will show
kana indicating different vowel values than we have in the modern
pronunciation -- mostly things like あう where the modern language has おう.
Historically, these were previously pronounced with an //au//
[diphthong](https://en.wikipedia.org/wiki/Diphthong) (two-vowel sound), which
was probably pronounced a bit like English _ow!_. This gradually flattened
from //au// to a long-vowel //ɔː// sound a bit like English _awww_ , and then
this //ɔː// shifted further to become modern //oː//, the long-O sound in
everyday Japanese.

These historical kana spellings -- and indicated pronunciations -- for
_on'yomi_ terms point towards the phonological shapes of the words when first
borrowed from Middle Chinese. 東 was borrowed originally with a pronunciation
probably like //tou// with that //u// on the end, and this flattened to modern
//oː//. See [the Chinese pronunciation section over at
Wiktionary](https://en.wiktionary.org/wiki/%E6%9D%B1#Pronunciation). While the
reconstructed Middle Chinese reading is shown as //tuŋ//, I've noticed after
much research that the modern Min Nan readings are sometimes closer to the
Japanese readings than the Middle Chinese reconstruction -- possibly due to
Min Nan being closer to the original dialect of Middle Chinese from which the
readings were borrowed into Japanese. One of the Min Nan pronunciations for 東
is listed as `tong`, and final //ŋ// in Chinese often correlates to an う in
the Japanese _on'yomi_.

Meanwhile, 刀 was borrowed as //tau//, and this shifted to modern //toː//. See
[the 刀 entry in Daijisen at Weblio](https://www.weblio.jp/content/%E5%88%80),
where again we see two kana spellings for the _on'yomi_ , listed as `トウ（タウ）`.
The （タウ） in parentheses is the historical kana spelling. And [the Middle
Chinese pronunciation](https://en.wiktionary.org/wiki/%E5%88%80#Pronunciation)
for this was reconstructed as //tɑu//.

## Conclusion about guessing kana spellings from pronunciations

Without knowing the origins of the term, you just _can't_ really tell whether
a long-O sound //oː// uses お or う as the second kana.

If you know at least whether the pronunciation is _on'yomi_ or _kun'yomi_ ,
it's often a good bet that long-O _kun'yomi_ -- in the middle of any word, and
not just the volitional / "let's" verb ending -- is spelled with an お for the
second kana, while long-O _on'yomi_ is spelled with an う for the second kana.




Responding to the extended discussion in the comments --

## Terminology

The second vowel is //o// in both 通【とお】り and 東【とう】. (東【とう】り is not a word, so
I won't repeat that here.) When you're talking about vowels, you're talking
about pronunciation. The second **kana** is either お or う, but in both 通【とお】り
or 東【とう】, the **vowel** is //o//.

## Kana spellings

This gets really involved. Hop to the bottom if the details don't matter to
you.

The kana spelling difference is due to different origins -- historically, 通り
came from older とほり. Medial (mid-word) //h//'s often
[lenited](https://en.wikipedia.org/wiki/Lenition) (softened) and disappeared
in many words, leaving behind the vowels. The pronunciation shifted before the
kana spelling did -- the とほり kana spelling was the "correct" spelling up
through the spelling reforms of the mid-20th century.

This older [historical kana
spelling](https://en.wikipedia.org/wiki/Historical_kana_orthography) is still
included in many monolingual Japanese dictionaries, since modern readers are
still likely to encounter this. For instance, see [the 通り entry at
Kotobank](https://kotobank.jp/word/%E9%80%9A%E3%82%8A-581994). At the top of
the page, you'll see kana spellings listed like `とおり〔とほり〕`. The kana string
〔in brackets〕 is the historical spelling.

### Historical spellings for native Japanese terms -- _kun'yomi_

If you spend some time with a monolingual Japanese dictionary that includes
these, you'll notice that many entries for _kun'yomi_ terms with vowel-vowel
combinations like //oo// or //au// come from older historical spellings with
an //h// or //f// in between.

All of the modern //h// or //f// kana, はひふへほ, were probably originally
pronounced with an initial //p//, as //pa pi pu pe po//. These lenited over
time to become first the bilabial fricative //ɸ//, kinda like an "f". We know
that these "f" pronunciations at the beginnings of words were still current in
1603, when the Japanese-to-Portuguese dictionary [the _Nippo
Jisho_](https://en.wikipedia.org/wiki/Nippo_Jisho) was published. We can see
this in the scanned copy over at Google Books, in entries like [on this page
for `F ANTES DO
I`](https://books.google.com/books?id=TFJAAQAAMAAJ&pg=PA87-IA1#v=onepage&q&f=false)
("F before I"), with entries like:

> **Fi**. _Sol_. ( **Fi**. Sun.)

Meanwhile, in a medial (mid-word) position, these pronunciations lenited
further to often become a //w// sound. We see that in places like the word 川,
modern かわ and historical かは. The _Nippo Jisho_ entry
[here](https://books.google.com/books?id=TFJAAQAAMAAJ&pg=PA43-IA1#v=onepage&q&f=false)
(right-hand column, sixth from the top) shows:

> **Caua**. _Rio, ou ribeira._ ( **Kawa**. River, or stream.)

In pretty much all cases except before //a//, this //w// sound basically
disappeared -- so Old Japanese //opo// ("big; many", the root of modern
大【おお】きい or the prefix 大【おお】) became early Middle Japanese //ofo//, then maybe
mid-Middle Japanese //owo//, and then recorded late Middle Japanese //oː//.

### Historical spellings for Chinese borrowings -- _on'yomi_

Entries for _on'yomi_ terms generally don't have this, and instead will show
kana indicating different vowel values than we have in the modern
pronunciation -- mostly things like あう where the modern language has おう.
Historically, these were previously pronounced with an //au//
[diphthong](https://en.wikipedia.org/wiki/Diphthong) (two-vowel sound), which
was probably pronounced a bit like English _ow!_. This gradually flattened
from //au// to a long-vowel //ɔː// sound a bit like English _awww_ , and then
this //ɔː// shifted further to become modern //oː//, the long-O sound in
everyday Japanese.

These historical kana spellings -- and indicated pronunciations -- for
_on'yomi_ terms point towards the phonological shapes of the words when first
borrowed from Middle Chinese. 東 was borrowed originally with a pronunciation
probably like //tou// with that //u// on the end, and this flattened to modern
//oː//. See [the Chinese pronunciation section over at
Wiktionary](https://en.wiktionary.org/wiki/%E6%9D%B1#Pronunciation). While the
reconstructed Middle Chinese reading is shown as //tuŋ//, I've noticed after
much research that the modern Min Nan readings are sometimes closer to the
Japanese readings than the Middle Chinese reconstruction -- possibly due to
Min Nan being closer to the original dialect of Middle Chinese from which the
readings were borrowed into Japanese. One of the Min Nan pronunciations for 東
is listed as `tong`, and final //ŋ// in Chinese often correlates to an う in
the Japanese _on'yomi_.

Meanwhile, 刀 was borrowed as //tau//, and this shifted to modern //toː//. See
[the 刀 entry in Daijisen at Weblio](https://www.weblio.jp/content/%E5%88%80),
where again we see two kana spellings for the _on'yomi_ , listed as `トウ（タウ）`.
The （タウ） in parentheses is the historical kana spelling. And [the Middle
Chinese pronunciation](https://en.wiktionary.org/wiki/%E5%88%80#Pronunciation)
for this was reconstructed as //tɑu//.

## Conclusion about guessing kana spellings from pronunciations

Without knowing the origins of the term, you just _can't_ really tell whether
a long-O sound //oː// uses お or う as the second kana.

If you know at least whether the pronunciation is _on'yomi_ or _kun'yomi_ ,
it's often a good bet that long-O _kun'yomi_ -- in the middle of any word, and
not just the volitional / "let's" verb ending -- is spelled with an お for the
second kana, while long-O _on'yomi_ is spelled with an う for the second kana.

