What is the significance of number 8 (八) in Japanese?


I've noticed a couple of words with the character 八 that have (seemingly)
nothing to do with the number 8.

  * 八百屋【やおや】 - greengrocer
  * 八つ【やつ】当たり【あたり】 - taking out anger on someone
  * 八丁【はっちょう】 - skillfullness

Furthermore, this is the only number which I've noticed this pattern on. All
other words consisting a number have a much more obvious relation, (even when
it's a 一).

* * *

On jisho.org, the [count of
#words](https://jisho.org/search/%E5%85%AB%20%23words) containing each of the
numeral characters shows a noticeable spike on 八 as well.

[code]

    一    二   三    四   五   六   七   八   九   十
    1713  787  1264  438  364  196  172  357  308  320
    
[/code]

* * *

And here's a table of how common each is in newspapers. Doesn't really show
anything but I thought to include it since I looked into it as well. I wonder
what the count would be if 九州【きゅうしゅう】 was stripped from the count on 九.

[code]

    一    二   三    四   五   六   七   八   九   十
    2     9    14    47   31   93   115  92   55   8
    
[/code]




This one puzzled me, so I did some digging.

I couldn't find anything definitive on where the "many" meaning may have come
from. This kanji _does_ seem to have this meaning in Chinese as well, as we
see over at [the Wiktionary entry for the Chinese
term](https://en.wiktionary.org/wiki/%E5%85%AB#Chinese), and also over in [the
Unihan entry](https://www.unicode.org/cgi-
bin/GetUnihanData.pl?codepoint=%E5%85%AB).

This is conjecture, but I suspect the "many" sense may come from the idea of
the eight directions -- the four cardinals, and the four in-betweens: north,
south, east, west, northeast, northwest, southeast, southwest.

The "many" sense appears to be quite old in Japanese, and it's specific to the
_kun'yomi_ or native Japanese term, so I don't think this was an import from
the Chinese. However, the sense development may have been similar in both
languages -- "eight" → "eight directions" → "all over, all directions" →
"many, various".




This one puzzled me, so I did some digging.

I couldn't find anything definitive on where the "many" meaning may have come
from. This kanji _does_ seem to have this meaning in Chinese as well, as we
see over at [the Wiktionary entry for the Chinese
term](https://en.wiktionary.org/wiki/%E5%85%AB#Chinese), and also over in [the
Unihan entry](https://www.unicode.org/cgi-
bin/GetUnihanData.pl?codepoint=%E5%85%AB).

This is conjecture, but I suspect the "many" sense may come from the idea of
the eight directions -- the four cardinals, and the four in-betweens: north,
south, east, west, northeast, northwest, southeast, southwest.

The "many" sense appears to be quite old in Japanese, and it's specific to the
_kun'yomi_ or native Japanese term, so I don't think this was an import from
the Chinese. However, the sense development may have been similar in both
languages -- "eight" → "eight directions" → "all over, all directions" →
"many, various".

