Pronunciation of 上下


上下 has lots of potential pronunciations:

  1. じょうげ
  2. うえした
  3. しょうか
  4. かみしも

Are there any guidelines on how to know which readings to use? I'm
particularly interested in this sentence:

> 顔が **上下** に割れるかと思ったほど大きくにっこりして、...  
>  _The person_ grinned so hard that he thought his face might split from top
> to bottom.

But I'd also be interested in more general thoughts.




As for your example, both じょうげ and うえした will work and I don't think I can
choose one.

The first reading
[じょうげ](https://dictionary.goo.ne.jp/jn/108085/meaning/m0u/%E4%B8%8A%E4%B8%8B/)
is the most versatile one that spans across a number of related meanings as
well as grammar:

  1. _n._ top and bottom, upper and lower, the former and the latter (volumes), inbound and outbound (traffic); ( _adverbially_ ) above and below
  2. _n._ all from top to bottom, high and low
  3. _n._ the quality of up and down, verticality, height, tallness, hierarchy, rank; ( _adjectively_ ) vertical, hierarchical
  4. _v._ move up and down, fluctuate, bounce; _n._ fluctuation, bouncing

[うえした](https://dictionary.goo.ne.jp/jn/17554/meaning/m0u/%E4%B8%8A%E4%B8%8B/)
and
[かみしも](https://dictionary.goo.ne.jp/jn/44835/meaning/m0u/%E4%B8%8A%E4%B8%8B/)
each shares a small portion of the definition #1 (and #3) shown above. You can
refer to [Ups and downs: かみ・しも vs
うえ・した](https://japanese.stackexchange.com/q/3090/7810) for their difference,
but simply put, うえした is used for something really "vertical", and かみしも
specially for those customarily assigned "up" and "down" and not very
"vertical".

  * うえした: for physical position, dimension, direction and hierarchy
  * かみしも: for river (up- and downstream), stage ("upper" (=left) and "lower" (=right)), kimono (top and bottom pieces), [tanka](https://en.wikipedia.org/wiki/Tanka) etc.

But うえした has one unique sense not in じょうげ: "upside down" by its own (=
上下（じょうげ・うえした）逆). The similar usage can also be seen in native words 前後ろ, 裏表,
右左 etc.

しょうか is... never used anymore, except that since it is all-漢音 reading, it must
(prescriptively) be used instead of じょうげ whenever [we read Classical
Chinese](https://en.wikipedia.org/wiki/Kanbun). For other meanings kindly
[consult the
dictionary](https://dictionary.goo.ne.jp/jn/107560/meaning/m0u/%E4%B8%8A%E4%B8%8B/),
because they are foreign to us too :)

> [故【ゆえ】に上下【しょうか】能【よ】く相【あい】親【した】しむなり。](https://kanbun.info/keibu/kokyo17.html)  
>  _Hence, as the superior and inferior, they are able to have an affection
> for each other._ ([James Legge](https://ctext.org/xiao-jing/service-of-the-
> ruler))




As for your example, both じょうげ and うえした will work and I don't think I can
choose one.

The first reading
[じょうげ](https://dictionary.goo.ne.jp/jn/108085/meaning/m0u/%E4%B8%8A%E4%B8%8B/)
is the most versatile one that spans across a number of related meanings as
well as grammar:

  1. _n._ top and bottom, upper and lower, the former and the latter (volumes), inbound and outbound (traffic); ( _adverbially_ ) above and below
  2. _n._ all from top to bottom, high and low
  3. _n._ the quality of up and down, verticality, height, tallness, hierarchy, rank; ( _adjectively_ ) vertical, hierarchical
  4. _v._ move up and down, fluctuate, bounce; _n._ fluctuation, bouncing

[うえした](https://dictionary.goo.ne.jp/jn/17554/meaning/m0u/%E4%B8%8A%E4%B8%8B/)
and
[かみしも](https://dictionary.goo.ne.jp/jn/44835/meaning/m0u/%E4%B8%8A%E4%B8%8B/)
each shares a small portion of the definition #1 (and #3) shown above. You can
refer to [Ups and downs: かみ・しも vs
うえ・した](https://japanese.stackexchange.com/q/3090/7810) for their difference,
but simply put, うえした is used for something really "vertical", and かみしも
specially for those customarily assigned "up" and "down" and not very
"vertical".

  * うえした: for physical position, dimension, direction and hierarchy
  * かみしも: for river (up- and downstream), stage ("upper" (=left) and "lower" (=right)), kimono (top and bottom pieces), [tanka](https://en.wikipedia.org/wiki/Tanka) etc.

But うえした has one unique sense not in じょうげ: "upside down" by its own (=
上下（じょうげ・うえした）逆). The similar usage can also be seen in native words 前後ろ, 裏表,
右左 etc.

しょうか is... never used anymore, except that since it is all-漢音 reading, it must
(prescriptively) be used instead of じょうげ whenever [we read Classical
Chinese](https://en.wikipedia.org/wiki/Kanbun). For other meanings kindly
[consult the
dictionary](https://dictionary.goo.ne.jp/jn/107560/meaning/m0u/%E4%B8%8A%E4%B8%8B/),
because they are foreign to us too :)

> [故【ゆえ】に上下【しょうか】能【よ】く相【あい】親【した】しむなり。](https://kanbun.info/keibu/kokyo17.html)  
>  _Hence, as the superior and inferior, they are able to have an affection
> for each other._ ([James Legge](https://ctext.org/xiao-jing/service-of-the-
> ruler))

