<p><a href="http://baike.baidu.com/subview/199191/8163691.htm" rel="nofollow">http://baike.baidu.com/subview/199191/8163691.htm</a> gives a plausible answer: it refers to a remote possibility of a thing X happening.  Sort of "among the ten thousand and one things that could happen, one is X."  Far back in ancient and classical Chinese,  the ten thousand things are a proverbial way to express all that happens in this world.  But I did not find sources giving any specific classical source for 万一 meaning "just in case." </p>

CC BY-SA 3.0
2016-02-04T17:18:11.680Z
looks like true. "In case (most unprobable) you die." 万一你死.
coobit
CC BY-SA 3.0
2016-02-04T21:30:21.560Z
A further support for the answer would be the saying 不怕一萬，祇怕萬一 

The ten thousand (regular scenarios) don't bother me; I only worry about the one in ten thousand (unlikely scenario).
monalisa
CC BY-SA 3.0
2016-02-04T17:15:04.290Z
2016-02-04T17:15:04.290Z
Colin McLarty
<p>Does anyone knows how 万一 became a phrase with "just in case" meaning?
Is it a shorthand of a longer phrase or chengyu?</p>

CC BY-SA 3.0
2016-02-11T04:24:32.187Z
It may help to consider that English has similar numerical/probability phrases: "in the thousand-to-one chance that ..."; "in the off-chance that ..."
Seralt
<etymology>
Does anyone know origins of 万一?
# Does anyone know origins of 万一?

(Asked by: username_0 on 2016-02-04)

Does anyone knows how 万一 became a phrase with "just in case" meaning?
Is it a shorthand of a longer phrase or chengyu?

**Tags:** etymology
> **Comments:**
> **username_1**: It may help to consider that English has similar numerical/probability phrases: "in the thousand-to-one chance that ..."; "in the off-chance that ..."  

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## 1 answers

### Answer by username_2 on 2016-02-04. Score: 2 | Accepted answer

<http://baike.baidu.com/subview/199191/8163691.htm> gives a plausible answer: it refers to a remote possibility of a thing X happening. Sort of "among the ten thousand and one things that could happen, one is X." Far back in ancient and classical Chinese, the ten thousand things are a proverbial way to express all that happens in this world. But I did not find sources giving any specific classical source for 万一 meaning "just in case."

> **Comments:**
> **username_0**: looks like true. "In case (most unprobable) you die." 万一你死.  
> **username_3**: A further support for the answer would be the saying 不怕一萬，祇怕萬一   The ten thousand (regular scenarios) don't bother me; I only worry about the one in ten thousand (unlikely scenario).  

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