<p>It comes from Nao(3)Bu(3) 脑补，which means someone says something very implicitly and you need to figure out the picture in your brain or the actual meaning of it in your brain.</p>

<p>so 脑补 can be literally understood as "Fill the holes in your brain" and thus 脑洞大开 means some phrase needs you really working hard in "脑补"</p>

CC BY-SA 3.0
2014-10-16T09:22:30.773Z
I guess it seems like a reasonable explanation. Although there are still occurrences online where I find the phrase used in completely unrelated meanings, I think it makes sense to interpret it as "being very creative" in a good number of places, which would fit with this origin.
Marc
CC BY-SA 3.0
2014-10-16T03:48:29.817Z
2014-10-16T03:48:29.817Z
Coderzelf
<p>It's a Network buzzwords.always used when someone says something dirty and others will daydream. I'm a little interested in how you know this word, As I know It's only popular in girls who like gay anime :P</p>

CC BY-SA 3.0
2014-10-16T11:13:18.430Z
Maybe that's where it originated (along with 脑补), I suppose, but nowadays it's quickly reaching memetic status and quite popular wherever I go, actually.
Marc
CC BY-SA 3.0
2014-10-16T13:30:33.967Z
"I'm a little interested in how you know this word, as I know it's only popular in girls who like gay anime", come on, anyone who's familiar with Weibo, etc. will know this phrase, OK? And it's not only a phrase for delusions of BL fandom!
xzczd
CC BY-SA 3.0
2014-10-16T09:45:27.837Z
2014-10-16T09:45:27.837Z
Peng  Zup
<p>Coderzelf's point about the origin of 脑洞 is correct (At least 脑洞 comes from 脑补 is the most accepted view) , but his explanation for 脑补 isn't so accurate. Though sometimes 脑补 is used to express "figure out the actual meaning of something very implicit", more frequently, this phrase is used for deliberate delusions. </p>

<p>Another possible origin of 脑洞 is it comes from the phrase 脑子进水, which means… er … "out of one's mind", so 脑洞大开 is sometimes used to express that something is foolish, but notice that this is mainly joking, not ironic.</p>

<p>BTW, 脑洞, 脑补, etc. are all new phrases and their meaning isn't completely stable currently, So their meaning may changed in the future. (Does anyone have the newest edition of 《现代汉语词典》 at hand? Has it included these phrases? They are included in some internet encyclopedias though. ) Here's a reference for 脑洞:</p>

<p><a href="http://zh.moegirl.org/%E8%84%91%E6%B4%9E" rel="nofollow">http://zh.moegirl.org/%E8%84%91%E6%B4%9E</a></p>

<hr>

<p>One thing I forgot to mention: Actually there's a tendency to use 脑洞大开 as a joking version of 异想天开. This isn't mentioned even in any internet encyclopedia, but it's true  as far as I can see.</p>

CC BY-SA 3.0
2014-10-16T14:00:40.190Z
2015-01-27T07:27:23.287Z
2015-01-27T07:27:23.287Z
xzczd
<p>腦洞大開 (Simplified: 脑洞大开) seems to be a phrase that's making its rounds in Sinophone online communities (a Google search may be illuminating), although its precise meaning as of yet still eludes me. It seems that different people have been using it to mean very different things. I've observed some using it to mean "thought-provoking", and others to mean essentially "exceedingly foolish".</p>

<p>What I wish to know, however, is if anyone has any idea where the phrase actually comes from. Being a student of mathematics, my obvious idea is the famous exclamation "my brain is open!" by Paul Erdős, the itinerant mathematician who uses the phrase to greet local mathematicians whenever he wanders to a new place. This meaning doesn't really correspond to the usage of the Chinese phrase, but it seems to be a plausible theory of its origin. Could anyone who follows Chinese online communities more closely than I do possibly shed some light on this neologism?</p>

CC BY-SA 3.0
2014-10-17T09:18:36.100Z
I hate the phrase.
sfy
CC BY-SA 3.0
2015-01-27T08:40:24.333Z
This phrase should come from the ACG (anime, comic & game) society. Very informal.
Stan
<etymology><idioms>
Thoughts on the expression 腦洞大開?
# Thoughts on the expression 腦洞大開?

(Asked by: username_0 on 2014-10-16)

腦洞大開 (Simplified: 脑洞大开) seems to be a phrase that's making its rounds in Sinophone online communities (a Google search may be illuminating), although its precise meaning as of yet still eludes me. It seems that different people have been using it to mean very different things. I've observed some using it to mean "thought-provoking", and others to mean essentially "exceedingly foolish".

What I wish to know, however, is if anyone has any idea where the phrase actually comes from. Being a student of mathematics, my obvious idea is the famous exclamation "my brain is open!" by Paul Erdős, the itinerant mathematician who uses the phrase to greet local mathematicians whenever he wanders to a new place. This meaning doesn't really correspond to the usage of the Chinese phrase, but it seems to be a plausible theory of its origin. Could anyone who follows Chinese online communities more closely than I do possibly shed some light on this neologism?

**Tags:** etymology, idioms
> **Comments:**
> **username_1**: I hate the phrase.  
> **username_2**: This phrase should come from the ACG (anime, comic & game) society. Very informal.  

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## 3 answers

### Answer by username_5 on 2014-10-16. Score: 3 | Accepted answer

Coderzelf's point about the origin of 脑洞 is correct (At least 脑洞 comes from 脑补 is the most accepted view) , but his explanation for 脑补 isn't so accurate. Though sometimes 脑补 is used to express "figure out the actual meaning of something very implicit", more frequently, this phrase is used for deliberate delusions.

Another possible origin of 脑洞 is it comes from the phrase 脑子进水, which means… er … "out of one's mind", so 脑洞大开 is sometimes used to express that something is foolish, but notice that this is mainly joking, not ironic.

BTW, 脑洞, 脑补, etc. are all new phrases and their meaning isn't completely stable currently, So their meaning may changed in the future. (Does anyone have the newest edition of 《现代汉语词典》 at hand? Has it included these phrases? They are included in some internet encyclopedias though. ) Here's a reference for 脑洞:

<http://zh.moegirl.org/%E8%84%91%E6%B4%9E>

---

One thing I forgot to mention: Actually there's a tendency to use 脑洞大开 as a joking version of 异想天开. This isn't mentioned even in any internet encyclopedia, but it's true as far as I can see.


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### Answer by username_3 on 2014-10-16. Score: 2

It comes from Nao(3)Bu(3) 脑补，which means someone says something very implicitly and you need to figure out the picture in your brain or the actual meaning of it in your brain.

so 脑补 can be literally understood as "Fill the holes in your brain" and thus 脑洞大开 means some phrase needs you really working hard in "脑补"

> **Comments:**
> **username_0**: I guess it seems like a reasonable explanation. Although there are still occurrences online where I find the phrase used in completely unrelated meanings, I think it makes sense to interpret it as "being very creative" in a good number of places, which would fit with this origin.  

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### Answer by username_4 on 2014-10-16. Score: 0

It's a Network buzzwords.always used when someone says something dirty and others will daydream. I'm a little interested in how you know this word, As I know It's only popular in girls who like gay anime :P

> **Comments:**
> **username_0**: Maybe that's where it originated (along with 脑补), I suppose, but nowadays it's quickly reaching memetic status and quite popular wherever I go, actually.  
> **username_5**: "I'm a little interested in how you know this word, as I know it's only popular in girls who like gay anime", come on, anyone who's familiar with Weibo, etc. will know this phrase, OK? And it's not only a phrase for delusions of BL fandom!  

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