61147
I am trying to understand why both 弟 and 第 kanji have the same 音読み
pronunciation ダイ/テイ? The common element
[弔](https://en.wiktionary.org/wiki/%E5%BC%94) is a variant of
[吊](https://en.wiktionary.org/wiki/%E5%90%8A#Chinese) - is its Chinese
pronunciation close to ダイ/テイ?
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2017-04-10T03:51:13.263
46426
2018-08-27T14:10:57.387
3371
question
etymology
Why both 弟 and 第 kanji have the same 音読み?
So [弟](http://jigen.net/kanji/24351) is actually a 象形{しょうけい} (pictograph) and
it is pronounced ダイ (among others of course).

On the other hand [第](http://jigen.net/kanji/31532) is a 形声{けいせい} (kanji in
which one element suggests the meaning and one the sound) and from the link
you can see that the pronunciation comes just from 弟. So I guess you should
really look at 弟 as the phonetic part rather than 弔.
CC BY-SA 4.0
2017-04-10T07:42:32.767
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2018-08-27T14:10:57.387
2018-08-27T14:10:57.387
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answer
They have the same _on'yomi_ because「弟」and「第」were originally the same
character, representing a word to do with _sequence_ or _order_ ; _younger
brother_ is an extension of this meaning (via _ordering of male siblings_
).「第」was created from「弟」by corrupting「丷」to「⺮」. In Mandarin Chinese, the two
characters also sound identical ([
**dì**](https://upload.wikimedia.org/wikipedia/commons/5/55/Zh-d%C3%AC.ogg)),
and bears distant similarity to **ダイ/テイ**.

Despite「弔」looking like it shows up in「弟」and「第」, they are unrelated.

> For reference,「弔」depicts a person「人」wielding a bird-capturing device; the
> device is comprised of an arrow attached to a very long rope, and is the
> original character of「/繳」.
>
> # `[商](https://en.wikipedia.org/wiki/Shang_dynasty)  
> [甲](https://en.wikipedia.org/wiki/Oracle_bone_script)  
> [![enter image description
> here](https://i.stack.imgur.com/I6Crs.png)](https://i.stack.imgur.com/I6Crs.png)  
>
> [甲](http://xiaoxue.iis.sinica.edu.tw/yanbian/Reference/JiaguwenReference)1870  
> [合集27738](http://www.guoxuedashi.com/jgwhj/?bhfl=1&bh=27738&jgwfl=)``  
> [篆](https://en.wikipedia.org/wiki/Small_seal_script)  
> [![enter image description
> here](https://i.stack.imgur.com/td3KC.png)](https://i.stack.imgur.com/td3KC.png)  
> [說文解字](https://en.wikipedia.org/wiki/Shuowen_Jiezi)  
>  ``現代  
> [楷](https://en.wikipedia.org/wiki/Regular_script)  
> [![enter image description
> here](https://i.stack.imgur.com/eQfxc.png)](https://i.stack.imgur.com/eQfxc.png)  
>  
>  `

* * *

「弟」is comprised of a handle of a pole-arm weapon「必」and a depiction of binding
rope inscribed in an「Ｓ」shape. It originally represented an ordered bundle of
weapon handles, extended to mean _order_ , then _ordered male siblings_ >
_younger brother_.

# `商  
甲  
[![enter image description
here](https://i.stack.imgur.com/i18VH.png)](https://i.stack.imgur.com/i18VH.png)  
[乙](http://xiaoxue.iis.sinica.edu.tw/yanbian/Reference/JiaguwenReference)8818  
``秦  
簡  
[![enter image description
here](https://i.stack.imgur.com/zIbng.png)](https://i.stack.imgur.com/zIbng.png)  
[睡](https://en.wikipedia.org/wiki/Shuihudi_Qin_bamboo_texts)ㆍ[日甲](http://xiaoxue.iis.sinica.edu.tw/yanbian/Reference/QinwenziReference)2  
``現代  
楷  
[![enter image description
here](https://i.stack.imgur.com/JXR5x.png)](https://i.stack.imgur.com/JXR5x.png)  
  
`

> 「必」is not related to「心」!「必」was originally「戈」([ _dagger-
> axe_](https://en.wikipedia.org/wiki/Dagger-axe)) with the blade part
> omitted, leaving the handle part. The modern meaning _certain_ is a phonetic
> loan.
>
> # `商  
> 甲  
> [![enter image description
> here](https://i.stack.imgur.com/SLz39.png)](https://i.stack.imgur.com/SLz39.png)  
>
> [乙](http://xiaoxue.iis.sinica.edu.tw/yanbian/Reference/JiaguwenReference)3069「必」  
> [合集14034](http://www.guoxuedashi.com/jgwhj/?bhfl=1&bh=14034&jgwfl=)``商  
> 甲  
> [![enter image description
> here](https://i.stack.imgur.com/0acal.png)](https://i.stack.imgur.com/0acal.png)  
>
> [甲](http://xiaoxue.iis.sinica.edu.tw/yanbian/Reference/JiaguwenReference)622「戈」  
> [合集33208](http://www.guoxuedashi.com/jgwhj/?bhfl=1&bh=33208&jgwfl=)`
>
> The handle part of the weapon is now written as「柲」. Later on, decorative
> marks were added to the character, leading to the modern form.
>
> # `[西周](https://en.wikipedia.org/wiki/Western_Zhou)  
> [金](https://en.wikipedia.org/wiki/Chinese_bronze_inscriptions)  
> [![enter image description
> here](https://i.stack.imgur.com/qhNXX.png)](https://i.stack.imgur.com/qhNXX.png)  
> 南宮乎鐘  
>
> [集成181](http://www.guoxuedashi.com/yzjwjc/?bh=181&jgwfl=)``[秦](https://en.wikipedia.org/wiki/Qin_dynasty)  
> [簡](https://en.wikipedia.org/wiki/Bamboo_and_wooden_slips)  
> [![enter image description
> here](https://i.stack.imgur.com/uAblp.png)](https://i.stack.imgur.com/uAblp.png)  
>
> 睡ㆍ[秦](http://xiaoxue.iis.sinica.edu.tw/yanbian/Reference/QinwenziReference)98  
>  ``現代  
> 楷  
> [![enter image description
> here](https://i.stack.imgur.com/fk5qY.png)](https://i.stack.imgur.com/fk5qY.png)  
>  
>  `
>
> Compare「心」, which depicts a heart with the heart chambers becoming
> exaggerated, then later heavily abbreviated.
>
> # `商  
> 甲  
> [![enter image description
> here](https://i.stack.imgur.com/H1lfh.png)](https://i.stack.imgur.com/H1lfh.png)  
>
> [甲](http://xiaoxue.iis.sinica.edu.tw/yanbian/Reference/JiaguwenReference)3510  
> [合集6](http://www.guoxuedashi.com/jgwhj/?bhfl=1&bh=6&jgwfl=)``西周  
> 金  
> [![enter image description
> here](https://i.stack.imgur.com/qHnlc.png)](https://i.stack.imgur.com/qHnlc.png)  
> 史墻盤  
>
> [集成10175](http://www.guoxuedashi.com/yzjwjc/?bh=10175&jgwfl=)``[楚](https://en.wikipedia.org/wiki/Chu_\(state\))  
> 簡  
> [![enter image description
> here](https://i.stack.imgur.com/nFbEM.png)](https://i.stack.imgur.com/nFbEM.png)  
>
> [包2](http://xiaoxue.iis.sinica.edu.tw/yanbian/Reference/ChuwenziReference).218  
>  ``  
> 篆  
> [![enter image description
> here](https://i.stack.imgur.com/Vk9d3.png)](https://i.stack.imgur.com/Vk9d3.png)  
> 說文解字  
>  ``[魏](https://en.wikipedia.org/wiki/Cao_Wei)  
> [隸](https://en.wikipedia.org/wiki/Clerical_script)  
> [![enter image description
> here](https://i.stack.imgur.com/KxOB4.png)](https://i.stack.imgur.com/KxOB4.png)  
> 上尊號奏  
>  ``現代  
> 楷  
> [![enter image description
> here](https://i.stack.imgur.com/1hYCB.png)](https://i.stack.imgur.com/1hYCB.png)  
>  
>  `

The「丷」part of「弟」was an eventual detachment from the main body of the handle.
In some variants,「丷」was corrupted into「艹」, [then again corrupted
into「⺮」](https://japanese.stackexchange.com/questions/42827/what-is-the-
character-etymology-of-%E7%9D%80?noredirect=1&lq=1), leading on to the modern
form of「第」, which preserves the meaning _order_ or _sequence_ and is not used
for the meaning _younger brother_.

# `秦  
簡  
[![enter image description
here](https://i.stack.imgur.com/zIbng.png)](https://i.stack.imgur.com/zIbng.png)  
睡ㆍ日甲2  
``[西漢](https://en.wikipedia.org/wiki/Han_dynasty#Western_Han)  
  
[![enter image description
here](https://i.stack.imgur.com/hCNBP.png)](https://i.stack.imgur.com/hCNBP.png)  
御食官鼎  
``[東漢](https://en.wikipedia.org/wiki/Han_dynasty#Eastern_Han)  
隸  
[![enter image description
here](https://i.stack.imgur.com/DCQRD.png)](https://i.stack.imgur.com/DCQRD.png)  
魯峻碑  
``現代  
楷  
[![enter image description
here](https://i.stack.imgur.com/yh29B.png)](https://i.stack.imgur.com/yh29B.png)  
  
`

* * *

# References:

  * 季旭昇《說文新證》
  * [小學堂](http://xiaoxue.iis.sinica.edu.tw/)
  * [國學大師](http://www.guoxuedashi.com/)
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2018-08-27T13:17:08.487
61147
2018-08-27T13:30:42.547
2020-06-17T08:18:27.500
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answer