Why is hot water sometimes called 开水? What is the meaning of "open" in this context? How is this different than saying 热水 or 烧水?

Is it something to do with how the water was made hot, kind of like how there are sometimes different words for frying something (炸,炒,etc.)?

  • It’s simply a somewhat metaphorical semantic extension of the basic meaning of 开 (‘open, activate, turn on’) applied to water. It’s not an extension that is very intuitive to an Anglophone, but it does make some sense that boiling water would be seen as ‘activating’ it and ‘opening it up’. You might expect that freezing water would then be called ‘closing’ it down and ice could be referred to as 关水, but I don’t think that exists. – Janus Bahs Jacquet Dec 25 '16 at 14:01

One of the meanings of 開 is 沸騰 (boiling) in 《漢語大辭典》開32.
It's nothing to do with "open" or "how".

開水 boiled water
熱水 hot water
燒水 to boil water

  • When the water is still very hot, we can use 開水 or 熱開水 as hot water.

  • When it is warm, we use 溫水 or 溫開水.

  • When it's at room temperature, we use 冷水 or 冷開水.

  • When it's below, say, 10℃, we use 冰水 or 冰開水.

開 can indicate that the water has been boiled. Without 開, it may or may not have been boiled.

The above Chinese words are used in Taiwan. They are probably different in the mainland.

  • 3
    It is also possible to use 开 as a verb in this meaning; 水开了 means the water has boiled; 汤煮开了之后 means "after the soup/broth has come to a boil". – Michaelyus Dec 24 '16 at 22:50
  • 开 is the simplified version of 開 – axsvl77 Dec 25 '16 at 13:26
  • @Michaelyus Most adjectives in Chinese could be used as verbs. That's nothing special. – user23013 Dec 25 '16 at 16:02
  • Thank you, I didn't realize 開 also had this meaning! – acee Dec 30 '16 at 17:36

开水 is the general term of boiled water, it's usually fresh boiled. 开 (boiled, not opened) indicates the temperature of the water and it doesn't mean water cooking.

热水 means hot or warm water, it must not been boiled before.

烧水 means water cooking. 烧 is the verb and 水 is the object.

There are many food cooking terms associated to water or steam. For example steaming 蒸, you can see the 4 dots there, which symbolize the fire。包子 is one of the most steamed Chinese food, it's steamed stuffed bun.

Another example is poaching 煮, which contains very similar structure. One famous food is called 水煮鱼 poached sliced fish in hot chili oil. Have a try ;-)

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I would like to argue against some of the answers above. 开水 means water that have been boiled, but not necessarily still boiling/hot. Actually, people use the expressions 凉开水 (cold, boiled water) or 凉白开 (where 水 is omitted, meaning cold, boiled tap water) frequently.

So, 开水 and hot water have significant overlaps but are not the same thing:

  • 开水 can be cold or even iced (冰开水), as mentioned above;
  • hot water (热水) is usually 开水 (especially when referring to drinking water), but not necessarily - hot bathing water is 热水, but not 开水 - as virtually no one boils bathing water.

Regarding the etymology of "开" as boiling, I have no definitive answer. My guess is that boiling water in a Chinese tripod (鼎) often results in the steam pushing the lid open, hence "开".


To answer this question, you have to understand that Chinese traditional characters are mostly came from pictographic scripts.

開 is the tractional style of 开

Then we focus on this character

the outside frame 門 is symbolize the door, (you can notice this character is really like an opening door)

the character inside 开 is like a boiler in the campfire

  • Thanks, I always thought that this was a pictograph of someone opening a door. Do you have a reference where I can read more about 开 referring to a boiler? – acee Dec 30 '16 at 17:37

It is a intersting problem and I want to answer why Chinese use "开" to draw the boiled water. People use teaketettle to hot up water and you can image that when the water is boiled, the pot lid will be flushed and open with the vapor. So Chinese describe the boiled water as open water which is "开水" in Chinese. It is really funny!

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