72754
> 虹は7色だ。  
>  Rainbow has 7 colors.  
>  There are 7 colors in rainbow.

Question:  
how to pronounce 7色 to make meaning [7 colors]?

Problem:  
七色 is not [7 colors].  
It is a special scientific term, meaning [7-prismatic-colors].  
We do not make [7 colors] meaning, if we pronounce this sentence like this.

> 虹は七色だ。  
>  [niji-wa nana-iro da]  
>  Rainbow is the seven prismatic colors (thing).
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2019-10-26T11:34:02.510
72753
2019-10-26T11:52:32.957
34165
question
pronunciation numbers
７色 vs 七色 for rainbow (7 colors vs 7 prismatic colors)
The counter for color is 色（ **しょく** ）. If you want to say "seven (different)
colors" without any idiomatic meaning, you can say ななしょく.

> 地図を[7色]{ななしょく}に塗り分ける  
>  to paint a map using seven different colors

When you say like this, the colors can be anything including gray, brown and
pink. Alternatively, you can just say 7つの色【いろ】.

* * *

The word
[七色【なないろ】](https://dictionary.goo.ne.jp/word/%E4%B8%83%E8%89%B2_%28%E3%81%AA%E3%81%AA%E3%81%84%E3%82%8D%29/),
in kanji, specifically refers to the seven colors of a rainbow. (I wouldn't
call this a scientific term...) It also means "a wide variety of", as in 七色の声.
CC BY-SA 4.0
2019-10-26T11:52:32.957
72754
2019-10-26T11:52:32.957
5010
72753
answer