When you’ve just started to learn Japanese, you might notice this: the Japanese adjective for blue and green is the same: あおい (or 青い). Even in modern times, the word “Aoi” is used to describe objects that are green. For example, the word green light or green apple uses the kanji 青: 青信号 (aoshingou) and 青りんご (aoringo).

This is where the confusion starts. Just recently (about 100 years ago, of course), the Japanese language was introduced to use another word for “green,” midori (みどり・緑). While every country has its own take on how it wants colors to be described, colors in Japanese are used differently depending on their parts of speech.

So what’s the explanation and history behind aoi (青い)? When should you use Midori and Aoi? Are they the same thing?

Keep in mind that あお (青) is a noun, while あおい (青い) is an adjective as we will be referring to them both.

Is Aoi (青い) Both Blue And Green?

In ancient Japan, only four colors existed — or, at least, acknowledged: 白 shiro (white), 黒 kuro (black), 赤 aka (red) and 青 ao (blue). However, these words are used to group particular hues and shades rather than actual colors. For example, different shades of blue in the past are now purple, gray, and green. As such, 青 has been widely used to describe green and blue; they’re essentially considered the same — not visually, but conceptually.

The Japanese language only got its unique word for green, みどり (緑), during the Heian period, which was between 794 and 1185. However, the term was not widely adopted until after World War II, and its late adoption was partly why we still see あおい used to describe green things.

The character 青 is mainly associated with words related to vegetation. Hence, words older than 緑 have remained unchanged. For example, words for “green apples” and “green vegetables” are still あおりんご (青林檎) and あおやさい (青野菜).

Not only does vegetation use the word for blue instead of green, but green traffic lights have been called 青信号 (あおしんごう) in Japanese. This can be translated to blue traffic light in English. This is because when traffic lights were first introduced in the 1930s, newspapers used あお or 青  to describe its color since the word for green had yet to be adopted. The word stayed; much like anything else in society, it refuses to change.

What About Other Colors?

The same can be seen in other basic color wheels. Kuro (くろ) and Shiro (しろ) are used to describe things that are dark and light — cool and warm. The word あか covers a spectrum of dark red, orange, and yellow, with lighter yellow colors grouped to しろ. Ki (黄) paints — no pun intended — on shades of yellow, gold, and lighter brown. Murasaki (むらさき) was once the name of a plant but eventually became a color name for purple, too.

みどり, like other newer words like ちゃいろ (茶色), which means brown, and きいろ (黄色), which means yellow, is a modern addition to the Japanese language.

Differences Between Aoi (青い) and Midori (緑)

The character 青 has been constantly evolving in both Chinese and Japanese Language. Pronounced as ‘qing’ in Chinese and ‘ao’ in Japanese, 青 can refer to relatively similar terms from both languages.

In Chinese, 青 is used to describe things that are (naturally) green, such as 青草 (green grass), 青山 (green mountain), 青島 (Qingdao). You should never use 青 to describe things that are not naturally green. For example, you would not call a green light 青燈, but rather, it should be called 綠燈 (ludeng)(綠 can be used to refer to anything green).

In Japanese, 青 is used to describe blue things, such as 青い空 (blue sky)、青い海 (blue ocean).

Aoi (青い) can also be translated to “fresh” or “newly grown”, such as vegetation which can have a blueish green color at times. It can also be referred to as an adjective to describe someone who is “inexperienced” or “fresh to the Industry.” However, keep in mind あおい isn’t loosely interchangeable with みどり.
So, just as a simple short hand, 青 can be used for both blue and green especially green produce or young leaves like grass (青草 or aokusa). However, 緑 is only used for green specifically and never blue. It is used for the word green tea or 緑茶 (ryokucha).

Common words that use “Ao” 青

The character (青) ao, represents light colors and is used in many Japanese words. Here are some words in which you will use 青 :  

• 青空 Aozora – Blue Skies
• 青い海 Aoiumi – Blue Ocean
• 青信号 Aoshingou  – Green Traffic Lights
• 青りんご Aoringo – Green apple
• 青春 Seishun – Youth
• 青森 Aomori – Aomori (city/prefecture)
• 青山 Aoyama – Green Mountain
• 青汁 Aojiru – Green Juice
• 青虫 Aomushi – Green Caterpillar (lit. green bug)

When To Use Aoi (青い) and Midori (緑)

It seems that most of the words in the table still use 青い for things that are actually green in color. This is because most of these words were around long before the word 緑 was widely adopted. But when you want to describe the color of something that’s not already its own word, you can use 緑 for green and 青い for blue. For instance:

• シャツは青いです。shatsu wa aoi desu. – My shirt is blue.

そのかえるは緑です。sono kaeru ha midori desu. – That frog is green.

FAQ

In many scenarios, aoi means both green and blue. It is not loosely interchangeable with each other, but in specific phrases, it is used differently due to the nature it describes.

Green is usually referred to as midori in Japanese, but green traffic light is aoi.

The word 緑 (midori or green) was introduced much later than the word 青い (aoi or blue) which described both green and blue since they considered to be in the same color range at the time. This is why many words today still use 青 to describe something that actually looks green since 緑 was not widely adopted until after WWII.

青い (aoi) can describe both green and blue in Japan, however, the 2 colors are distinguished from each other. Although many words for things that look green still use 青 like (青信号 or green light), you would use the word 緑 to describe something as green. For example, その木は緑です。sono ki ha midori desu or that tree is green.