Colors in Japanese: Why do green and blue use the same character?

In Japanese, the traffic light is blue, not green …

For language learners, perhaps one of the most confusing moments is when they learn the colors in Japanese. This especially happens in the case of green and blue, which are represented by the character 青 (あ お).

Even today, for some things the character is still used for both colors: Instead of saying “green light” (緑 信号), it is said “blue light” (青 信号). To understand this, we must go back to ancient times when there were only four categories of colors.

Colors in Japanese: Four Categories

Colors in Japanese: Sometimes it is difficult to draw a line between blue and green.
Colors in Japanese: Sometimes it is difficult to draw a line between blue and green.

In the Nara and Heian periods there were only four adjectives to describe colors in Japanese: 「白 し」 、 「赤 し」 、 「青 し」 、 「黒 し」 (white, red, blue / green and black), that is, the entire range of colors that we recognize today fell into one of four categories.

In other words, the term for each color back then covered a wider spectrum of colors than it does today. The character
青 was not only used to refer to blue, but also to green, even purple and gray! That is why today there are still words like 「青 リ ン ゴ」 (green apple) 、 「青 汁」 (green broth) 、 「青 の り」 (green algae) 、 「青虫」 (cabbage larva) 、 「青 じ そ」 ( shiso) 、 「青 ね ぎ」 、 「青菜」 (vegetables) are still used today.

In other words, today the character
青 because in the Nara and Heian periods it was used for these two (and more) colors.

In the same period, for example, yellow was also considered to be a color close to red, so the character
赤 for both. Even before, the same character was used instead of 明 (bright, clear) for words like 「赤 の 他人」 (total unknown) 、 「赤 恥」 (disgrace, shame).

Interestingly in the pre-war period, officially the name of the green light was 「緑 信号」 (with the character for “green”), but due to the widespread use of 「青 信号」 it was eventually recognized as the official name. Even up to the Showa period the lights were “greener”, but to make more sense to call them 青 信号, and to be more inclusive with people with color blindness, the lights are more “blue”.

The Japanese it is not the only language which originally had fewer categories for colors. There are even civilizations that only distinguished two categories: light colors (white) and dark colors (black). This phenomenon has been the object of study by several linguists.