Etymology of 宵【よい】


This is a loose follow-up of [my first question here on
JLSE](https://japanese.stackexchange.com/questions/6581/kanji-for-native-
japanese-concepts-kunyomi-spanning-multiple-morphemes). I tried to check
[gogen-allguide.com](http://gogen-allguide.com/) and 大辞林, but couldn't find
anything definitive. Unfortunately I don't know any other resources for
checking etymologies for (native) Japanese words.

So, my question is: What is the etymology of 宵【よい】? My guess would be
夜(よ)日(ひ).




[Gogen Allguide](http://gogen-allguide.com/yu/yuube.html) and my dead-tree
version of Sh­ōgakukan Kokugo Dai Jiten in JA mention that, in the Heian
period and earlier, the terms for "evening, night" were somewhat specific,
going in order:

  * ゆうべ  
Early evening

  * よい  
Late evening, early night: dusk

  * よなか  
Night

  * あかとき  
Pre-dawn

  * あけぼの  
Dawn

I can't find anything definitive at present about the derivation of 宵. I do
note, however, that 夜日 is a separate word in its own right, _yohi_ : "night
and day, day and night". So that's probably not the source of 宵.

I do see that the older kana spelling was よひ. I note also that 夕 _yū_ of
similar meaning has an older kana spelling of ゆふ. I wonder then if these two
might be cognate, with よひ representing some kind of inflection. Or, possibly,
よひ might be the noun stem form of a hypothetical verb よふ, consisting of 夜
"night" + ふ "suffix indicating iterative or continuous action, or ongoing
change". That said, I can't find evidence of any such verb in my sources to
hand.

* * *

**_Update._**

The link to JSTOR that snailboat added above in a comment previously didn't
work for me, possibly due to net congestion or server trouble. I have since
read through that paper by J. Marshall Unger, [_New Etymologies for Some
Japanese Time-
Words_](http://www.jstor.org/discover/10.2307/25766944?uid=372503961&uid=2&uid=3&uid=60&sid=21103670524981).
In it, he provides the following theory on page 40 for the derivation of
modern 宵{よい}, ancient _yopi_ (my additions in [square brackets] for clarity):

> Because free native nouns in Old Japanese could begin with _p_ but not _r_ ,
> the derivation of _yopi_ 'evening twilight' is not as problematic as that of
> _yoru_ , though by no means certain. It was probably a relatively late
> reduction of a whole phrase such as _* yo pikari_ 'night shining', with the
> same _* yo_ 'night' morpheme. According to pJ [proto-Japanese] non-final
> mid-vowel raising, an ancient compound of the form _* yo-pi_ would have
> yielded OJ [Old Japanese] _* yupi_, not _yopi_ , and OJ _pi_ 'sun, day' was
> not used for 'light'.

I'm not sure what _pJ non-final mid-vowel raising_ is beyond the summary
provided by Unger (apparently outlined in more detail in a separate paper by
Frellesvig and Whitman in 2004), but from the context of Unger's paper, I find
myself unconvinced—there are OJ terms that don't seem to exhibit this
purported _yo-_ > _yu-_ shift. I'm also unconvinced that _pikari_ would
shorten to just _pi_ , given that in all other contexts that I'm aware of, the
shortest form is _pika_ , though I am certainly open to some other term being
the cognate source for the _-pi_ in _yopi_.




[Gogen Allguide](http://gogen-allguide.com/yu/yuube.html) and my dead-tree
version of Sh­ōgakukan Kokugo Dai Jiten in JA mention that, in the Heian
period and earlier, the terms for "evening, night" were somewhat specific,
going in order:

  * ゆうべ  
Early evening

  * よい  
Late evening, early night: dusk

  * よなか  
Night

  * あかとき  
Pre-dawn

  * あけぼの  
Dawn

I can't find anything definitive at present about the derivation of 宵. I do
note, however, that 夜日 is a separate word in its own right, _yohi_ : "night
and day, day and night". So that's probably not the source of 宵.

I do see that the older kana spelling was よひ. I note also that 夕 _yū_ of
similar meaning has an older kana spelling of ゆふ. I wonder then if these two
might be cognate, with よひ representing some kind of inflection. Or, possibly,
よひ might be the noun stem form of a hypothetical verb よふ, consisting of 夜
"night" + ふ "suffix indicating iterative or continuous action, or ongoing
change". That said, I can't find evidence of any such verb in my sources to
hand.

* * *

**_Update._**

The link to JSTOR that snailboat added above in a comment previously didn't
work for me, possibly due to net congestion or server trouble. I have since
read through that paper by J. Marshall Unger, [_New Etymologies for Some
Japanese Time-
Words_](http://www.jstor.org/discover/10.2307/25766944?uid=372503961&uid=2&uid=3&uid=60&sid=21103670524981).
In it, he provides the following theory on page 40 for the derivation of
modern 宵{よい}, ancient _yopi_ (my additions in [square brackets] for clarity):

> Because free native nouns in Old Japanese could begin with _p_ but not _r_ ,
> the derivation of _yopi_ 'evening twilight' is not as problematic as that of
> _yoru_ , though by no means certain. It was probably a relatively late
> reduction of a whole phrase such as _* yo pikari_ 'night shining', with the
> same _* yo_ 'night' morpheme. According to pJ [proto-Japanese] non-final
> mid-vowel raising, an ancient compound of the form _* yo-pi_ would have
> yielded OJ [Old Japanese] _* yupi_, not _yopi_ , and OJ _pi_ 'sun, day' was
> not used for 'light'.

I'm not sure what _pJ non-final mid-vowel raising_ is beyond the summary
provided by Unger (apparently outlined in more detail in a separate paper by
Frellesvig and Whitman in 2004), but from the context of Unger's paper, I find
myself unconvinced—there are OJ terms that don't seem to exhibit this
purported _yo-_ > _yu-_ shift. I'm also unconvinced that _pikari_ would
shorten to just _pi_ , given that in all other contexts that I'm aware of, the
shortest form is _pika_ , though I am certainly open to some other term being
the cognate source for the _-pi_ in _yopi_.

