<p>Check out the two entries in <em>A Student's Dictionary of Classical and Medieval Chinese</em> for when to use 于 and not 於:</p>

<blockquote>
  <p>於</p>
  
  <p>MC 'jo</p>
  
  <p>1 (GP) typically occurs after a VB or VB-phrase and before a noun or noun-phrase, indicating any indirect or locative relation: in, at, from, to, on, with regard to, vis-à-vis, etc.; e.g. 王坐於堂上 wáng zuò yú tángshàng, The king was sitting in the hall; 千里之行始於足下 qiānlǐzhi xíng shǐ yú zúxià, A journey of a thousand li starts from under one’s foot; 敏於事而慎於言 mǐn yú shì ér shèn yú yán, diligent vis-à-vis affairs and careful vis-à-vis speech; cog. yú 于 in, at, from, to, on, with regard to, etc.</p>
  
  <p>N.B. Fom the Warring States period on 于 yú and 於 yú are generally interchangeable, save for stylistic preferences; prior to the Warring States period 於 yú is rare, and the two are not equivalent to each other.</p>
  
  <p>a) (GP) after a VB or VB-phrase and before a noun or noun-phrase, indicating comparative sense: than; e.g. 民少於今日 mín shǎo yú jīnrì, The citizens were fewer in number than [those of] the present day; 青於藍 qīng yú lán, bluer than indigo.</p>
  
  <p>2 (Budd.) (GP) in Budd. texts often simply a marker preceding the obj, with no translatable meaning.</p>
</blockquote>

<hr>

<blockquote>
  <p>于</p>
  
  <p>MC hju</p>
  
  <p>1 typically occurs after a VB or VB-phrase and before a noun or noun-phrase, indicating any indirect or locative relation: in, at, from, to, on, with regard to, vis-à-vis, etc.; e.g. 入于幽谷 rù yú yōugǔ, entering into a dark valley; 君告于天子 jūn gào yú tiānzǐ, The lord reported it to the Son of Heaven; cog. yú 於 in, at, from, to, on, with regard to, etc.
  N.B. From the Warring States period on 于 yú and 於 yú are generally interchangeable, save for stylistic preferences; prior to the Warring States period they are not equivalent to each other.</p>
  
  <p>a) preceding a time-word (and often after zhì 至): arriving at, up to, at [the time in question]; e.g. 而至于今 érzhì yú jīn, and still it continues up to the present; 于時以為蜀得其龍 yú shí yǐwéi shǔ dé qí lóng, by that time they figured that Shu had gotten its dragon; 二世三世至于萬世 èrshì sānshì zhì yú wànshì, for two generations, three generations, up to a myriad of generations. </p>
  
  <p>b) after a VB or VB-phrase and before a noun or noun-phrase, indicating comparative sense: than; e.g. 多于前功 duō yú qiángōng, more than previous merit; 異于今人 yì yú jīnrén, more unusual than people of the present day.</p>
  
  <p>2 pre-classical VB prefix of uncertain meaning, possibly an inchoative sense or rhetorical emphasis; e.g. 黃鳥于飛 huángniǎo yú fēi, The yellow birds are taking to flight; 之子于歸 zhīzǐ yú guī, That fellow is on his way home.</p>
  
  <p>3 (bn.) 于闐 yútián (MC hju-den), Khotan, oasis city on the southern Silk Road in the Tarim Basin, the main source of nephrite imported to China.</p>
  
  <p>4 arch-shaped rim or sound-bow of a chime-bell’s mouth.</p>
</blockquote>

<hr>

<p>You can see from the reconstructions that 於 and 于 didn't even share a common pronunciation.</p>

<p>These are classical and medieval usages though. In modern Chinese the difference is less obvious.</p>

<hr>

<p>The usage of 致力于 and 歸于 on <a href="https://www.taiwanus.net/E/E_4/E_4_01.htm" rel="nofollow noreferrer">that site you linked above</a> is somewhat baffling. 两岸 has entries for: 致力於 <a href="https://www.moedict.tw/~%E8%87%B4%E5%8A%9B%E6%96%BC" rel="nofollow noreferrer">https://www.moedict.tw/~%E8%87%B4%E5%8A%9B%E6%96%BC</a> and 歸於 <a href="https://www.moedict.tw/~%E6%AD%B8%E6%96%BC" rel="nofollow noreferrer">https://www.moedict.tw/~%E6%AD%B8%E6%96%BC</a> Taiwan's Ministry of Education certainly doesn't see any reason to use 于 over 於.</p>

<p>MoE does make some distinctions as well:</p>

<blockquote>
  <p><a href="https://www.moedict.tw/~%E4%BA%8E" rel="nofollow noreferrer">于ㄩˊ</a></p>
  
  <p>介詞：</p>
  
  <p>➊ ​引進時間、地點、範圍等，相當於「在」。例 「生于1949年」、「發源于黃河」、「耿耿于懷」。</p>
  
  <p>➋ ​引進方面、原因、目的。例 「勇于承擔」、「死于車禍」、「急于做到」。</p>
  
  <p>➌ ​引進方向、目標。例 「言歸于好」、「嫁禍于他人」、「獻身于教育」。</p>
  
  <p>➍ ​引進對象，相當於「向」、「給」、「對」。例 「忠于國家」、「有益于人民」、「無濟于事」。</p>
  
  <p>➎ ​引進比較的對象。例 「重于泰山」、「輕于鴻毛」、「高于樓臺」。</p>
  
  <p>➏ ​引進行為的主動者。例 「死于槍手」、「限于篇幅，暫不刊登」、「國家隊竟敗于默默無聞的隊伍」。</p>
  
  <p>➐ ​引進來源、起點，相當於「從」、「自」。例 「青出于藍」、「佛教發源于印度」。
      ∥也作「於」（陸 今不用）​。</p>
  
  <p>助詞。用在句首或句中，無意義。例 「鳳凰于飛」、「之子于歸」。</p>
  
  <p>姓。</p>
</blockquote>

<p>and</p>

<blockquote>
  <p><a href="https://www.moedict.tw/~%E6%96%BC" rel="nofollow noreferrer">於ㄩˊ</a></p>
  
  <p>简于</p>
  
  <p>介詞：</p>
  
  <p>引進地點、範圍、時間等，相當於「在」。例 「飯店位於機場對面」、「於無意中發現這個祕密」、「生於70年代」。</p>
  
  <p>引進對象，相當於「向」、「給」、「對」。例 「問道於盲」、「於事無補」、「己所不欲，勿施於人」。</p>
  
  <p>引進來源、起點，相當於「從」、「自」。例 「青出於藍」、「佛教發源於印度」。</p>
  
  <p>引進行為的主動者。例 「地主隊敗於客隊」、「見笑於大方之家」、「限於篇幅，忍痛割愛」。</p>
  
  <p>引進方向、目標。例 「天氣逐漸趨於穩定」、「致力於學術研究」。</p>
  
  <p>引進方面、原因、目的。例 「勇於負責」、「苦於沒有機會」、「執著於實現理想」。</p>
  
  <p>引進比較的對象。例 「重於泰山」、「苛政猛於虎」、「成長率高於預期」。
      ∥也作「于」。</p>
</blockquote>

<p>Most of the definitions are more or less the same and it's quite hairy in general.</p>

CC BY-SA 3.0
2018-03-15T12:41:12.670Z
In the front matter of *A Student's Dictionary of Classical and Medieval Chinese*, does it specify what they mean by *reconstructions*? This term obviously applies only to *words*, which makes it ambiguous when words and characters have a many-to-many relationship.
dROOOze
CC BY-SA 3.0
2018-03-15T14:24:10.433Z
@droooze Sorry, maybe *I* was unclear. I was talking about the MC pronunciations only. I believe they're provided by William Baxter.
Mou某
CC BY-SA 3.0
2018-03-15T09:30:24.273Z
2018-03-15T10:05:56.300Z
2018-03-15T10:05:56.300Z
Mou某
<p><em>This answer details a bit of history of the development of</em>「于」<em>and</em>「於」, <em>and addresses why they overlap. It is purely meant to be a complement to @user3306356's answer, which has responded to the question directly.</em></p>

<hr>

<p>In the Modern Chinese language shared across all Chinese-using regions,「于」and「於」largely represents the same overlapping preposition/adposition function. <em>For this function only</em>*, any proposed "rules" specifying the difference in usage between the two are very unlikely to be accepted across all Chinese-speaking regions, mainly complicated by the fact that PRC has made「於」obsolete and Taiwan has a habit of using「於」and not「于」. This is also why you wouldn't find「于」on all but the most thorough Taiwan-Chinese input methods.</p>

<hr>

<p>「于」and「於」are both phonetic loans; they both originally represented something else.</p>

<blockquote>
  <h1>Glyph origin of 于</h1>
  
  <p>「于」was originally a picture of a wind instrument:</p>
  
  <p><a href="https://i.sstatic.net/z73v1.png" rel="noreferrer"><img src="https://i.sstatic.net/z73v1.png" alt="enter image description here"></a></p>
  
  <p>It was later simplified to</p>
  
  <p><a href="https://i.sstatic.net/RiSOR.png" rel="noreferrer"><img src="https://i.sstatic.net/RiSOR.png" alt="enter image description here"></a></p>
  
  <p>then further simplified to「于」. The original sense of the wind instrument is now written「竽」after「于」became extensively used for its grammatical function meaning and had lost its original meaning.</p>
  
  <h1>Glyph origin of 於</h1>
  
  <p>「於」and「烏」were originally the same character, but have been graphically differentiated. For reference, their development looked something like</p>
  
  <p><a href="https://i.sstatic.net/arG0a.png" rel="noreferrer"><img src="https://i.sstatic.net/arG0a.png" alt="enter image description here"></a>
  <a href="https://i.sstatic.net/oGK75.png" rel="noreferrer"><img src="https://i.sstatic.net/oGK75.png" alt="enter image description here"></a></p>
  
  <p>There was absolutely no difference between the characters「於」and「烏」before the Qin dynasty, and「烏/於」was used for its current grammatical function long before they became different characters.</p>
</blockquote>

<hr>

<p>The historical usage of「于」and「於」goes in accordance to something like the following timeline:</p>

<ul>
<li><p>Western Zhou</p>

<ul>
<li>Only「于」is used for the grammatical function.</li>
<li>During the same period,「於」is used as an exclamation.</li>
<li>This is especially obvious when both「于」and「於」appear simultaneously: <a href="https://i.sstatic.net/SPP6X.png" rel="noreferrer"><img src="https://i.sstatic.net/SPP6X.png" alt="enter image description here"></a></li>
</ul></li>
<li><p>Late Western Zhou to end of the Spring and Autumn period:</p>

<ul>
<li>「于」sees an additional use of a filler syllable to match rhythms across commonly used phrases.</li>
<li>「於」gains the grammatical function of what was previously「于」, but「于」still sees higher usage frequency for this function, and there is no difference between the two in this context.</li>
<li>「於」still kept its previous meaning (as an exclamation).</li>
</ul></li>
<li>Warring States and later:

<ul>
<li>「於」overtakes「于」in frequency in the grammatical function sense, but both were still used and neither was permanently dropped.</li>
</ul></li>
</ul>

<p>See also <a href="http://www.cuhk.edu.hk/ics/clrc/crcl_94_1/yang.pdf" rel="noreferrer">從“于 / 於”用法上的變化看複合詞“於是”的產生</a>.</p>

<hr>

<p>*There are differences between「于」and「於」when they're not used in the grammatical function sense, which this answer touches upon but doesn't explain thoroughly - detailed dictionaries will provide a more comprehensive explanation.</p>

CC BY-SA 3.0
2018-03-15T10:37:22.150Z
2018-03-15T11:40:28.273Z
2018-03-15T11:40:28.273Z
dROOOze
<p>On my last <a href="https://chinese.stackexchange.com/q/29090/11365">question</a>, there is a hint not to treat 於 as the traditional variant of 于。However, my keyboard (Tw) never proposes 于。 </p>

<p>I also noted that the commentary on the 學而 on this <a href="https://www.taiwanus.net/E/E_4/E_4_01.htm" rel="noreferrer">site</a> uses 于 twice. The text and commentary combined use 於 nine times. Can anyone enlighten me?</p>

<grammar><traditional-characters>
When to use 于 and not 於 in traditional Chinese?
# When to use 于 and not 於 in traditional Chinese?

(Asked by: username_0 on 2018-03-15)

On my last [question](https://chinese.stackexchange.com/q/29090/11365), there is a hint not to treat 於 as the traditional variant of 于。However, my keyboard (Tw) never proposes 于。

I also noted that the commentary on the 學而 on this [site](https://www.taiwanus.net/E/E_4/E_4_01.htm) uses 于 twice. The text and commentary combined use 於 nine times. Can anyone enlighten me?

**Tags:** grammar, traditional-characters

---

## 2 answers

### Answer by username_1 on 2018-03-15. Score: 4 | Accepted answer

Check out the two entries in *A Student's Dictionary of Classical and Medieval Chinese* for when to use 于 and not 於:

> 於
>
> MC 'jo
>
> 1 (GP) typically occurs after a VB or VB-phrase and before a noun or noun-phrase, indicating any indirect or locative relation: in, at, from, to, on, with regard to, vis-à-vis, etc.; e.g. 王坐於堂上 wáng zuò yú tángshàng, The king was sitting in the hall; 千里之行始於足下 qiānlǐzhi xíng shǐ yú zúxià, A journey of a thousand li starts from under one’s foot; 敏於事而慎於言 mǐn yú shì ér shèn yú yán, diligent vis-à-vis affairs and careful vis-à-vis speech; cog. yú 于 in, at, from, to, on, with regard to, etc.
>
> N.B. Fom the Warring States period on 于 yú and 於 yú are generally interchangeable, save for stylistic preferences; prior to the Warring States period 於 yú is rare, and the two are not equivalent to each other.
>
> a) (GP) after a VB or VB-phrase and before a noun or noun-phrase, indicating comparative sense: than; e.g. 民少於今日 mín shǎo yú jīnrì, The citizens were fewer in number than [those of] the present day; 青於藍 qīng yú lán, bluer than indigo.
>
> 2 (Budd.) (GP) in Budd. texts often simply a marker preceding the obj, with no translatable meaning.

---

> 于
>
> MC hju
>
> 1 typically occurs after a VB or VB-phrase and before a noun or noun-phrase, indicating any indirect or locative relation: in, at, from, to, on, with regard to, vis-à-vis, etc.; e.g. 入于幽谷 rù yú yōugǔ, entering into a dark valley; 君告于天子 jūn gào yú tiānzǐ, The lord reported it to the Son of Heaven; cog. yú 於 in, at, from, to, on, with regard to, etc.
> N.B. From the Warring States period on 于 yú and 於 yú are generally interchangeable, save for stylistic preferences; prior to the Warring States period they are not equivalent to each other.
>
> a) preceding a time-word (and often after zhì 至): arriving at, up to, at [the time in question]; e.g. 而至于今 érzhì yú jīn, and still it continues up to the present; 于時以為蜀得其龍 yú shí yǐwéi shǔ dé qí lóng, by that time they figured that Shu had gotten its dragon; 二世三世至于萬世 èrshì sānshì zhì yú wànshì, for two generations, three generations, up to a myriad of generations.
>
> b) after a VB or VB-phrase and before a noun or noun-phrase, indicating comparative sense: than; e.g. 多于前功 duō yú qiángōng, more than previous merit; 異于今人 yì yú jīnrén, more unusual than people of the present day.
>
> 2 pre-classical VB prefix of uncertain meaning, possibly an inchoative sense or rhetorical emphasis; e.g. 黃鳥于飛 huángniǎo yú fēi, The yellow birds are taking to flight; 之子于歸 zhīzǐ yú guī, That fellow is on his way home.
>
> 3 (bn.) 于闐 yútián (MC hju-den), Khotan, oasis city on the southern Silk Road in the Tarim Basin, the main source of nephrite imported to China.
>
> 4 arch-shaped rim or sound-bow of a chime-bell’s mouth.

---

You can see from the reconstructions that 於 and 于 didn't even share a common pronunciation.

These are classical and medieval usages though. In modern Chinese the difference is less obvious.

---

The usage of 致力于 and 歸于 on [that site you linked above](https://www.taiwanus.net/E/E_4/E_4_01.htm) is somewhat baffling. 两岸 has entries for: 致力於 <https://www.moedict.tw/~%E8%87%B4%E5%8A%9B%E6%96%BC> and 歸於 <https://www.moedict.tw/~%E6%AD%B8%E6%96%BC> Taiwan's Ministry of Education certainly doesn't see any reason to use 于 over 於.

MoE does make some distinctions as well:

> [于ㄩˊ](https://www.moedict.tw/~%E4%BA%8E)
>
> 介詞：
>
> ➊ ​引進時間、地點、範圍等，相當於「在」。例 「生于1949年」、「發源于黃河」、「耿耿于懷」。
>
> ➋ ​引進方面、原因、目的。例 「勇于承擔」、「死于車禍」、「急于做到」。
>
> ➌ ​引進方向、目標。例 「言歸于好」、「嫁禍于他人」、「獻身于教育」。
>
> ➍ ​引進對象，相當於「向」、「給」、「對」。例 「忠于國家」、「有益于人民」、「無濟于事」。
>
> ➎ ​引進比較的對象。例 「重于泰山」、「輕于鴻毛」、「高于樓臺」。
>
> ➏ ​引進行為的主動者。例 「死于槍手」、「限于篇幅，暫不刊登」、「國家隊竟敗于默默無聞的隊伍」。
>
> ➐ ​引進來源、起點，相當於「從」、「自」。例 「青出于藍」、「佛教發源于印度」。
> ∥也作「於」（陸 今不用）​。
>
> 助詞。用在句首或句中，無意義。例 「鳳凰于飛」、「之子于歸」。
>
> 姓。

and

> [於ㄩˊ](https://www.moedict.tw/~%E6%96%BC)
>
> 简于
>
> 介詞：
>
> 引進地點、範圍、時間等，相當於「在」。例 「飯店位於機場對面」、「於無意中發現這個祕密」、「生於70年代」。
>
> 引進對象，相當於「向」、「給」、「對」。例 「問道於盲」、「於事無補」、「己所不欲，勿施於人」。
>
> 引進來源、起點，相當於「從」、「自」。例 「青出於藍」、「佛教發源於印度」。
>
> 引進行為的主動者。例 「地主隊敗於客隊」、「見笑於大方之家」、「限於篇幅，忍痛割愛」。
>
> 引進方向、目標。例 「天氣逐漸趨於穩定」、「致力於學術研究」。
>
> 引進方面、原因、目的。例 「勇於負責」、「苦於沒有機會」、「執著於實現理想」。
>
> 引進比較的對象。例 「重於泰山」、「苛政猛於虎」、「成長率高於預期」。
> ∥也作「于」。

Most of the definitions are more or less the same and it's quite hairy in general.

> **Comments:**
> **username_2**: In the front matter of *A Student's Dictionary of Classical and Medieval Chinese*, does it specify what they mean by *reconstructions*? This term obviously applies only to *words*, which makes it ambiguous when words and characters have a many-to-many relationship.  
> **username_1**: @droooze Sorry, maybe *I* was unclear. I was talking about the MC pronunciations only. I believe they're provided by William Baxter.  

---

### Answer by username_2 on 2018-03-15. Score: 7

*This answer details a bit of history of the development of*「于」*and*「於」, *and addresses why they overlap. It is purely meant to be a complement to @user3306356's answer, which has responded to the question directly.*

---

In the Modern Chinese language shared across all Chinese-using regions,「于」and「於」largely represents the same overlapping preposition/adposition function. *For this function only*\*, any proposed "rules" specifying the difference in usage between the two are very unlikely to be accepted across all Chinese-speaking regions, mainly complicated by the fact that PRC has made「於」obsolete and Taiwan has a habit of using「於」and not「于」. This is also why you wouldn't find「于」on all but the most thorough Taiwan-Chinese input methods.

---

「于」and「於」are both phonetic loans; they both originally represented something else.

> # Glyph origin of 于
>
> 「于」was originally a picture of a wind instrument:
>
> [![enter image description here](https://i.sstatic.net/z73v1.png)](https://i.sstatic.net/z73v1.png)
>
> It was later simplified to
>
> [![enter image description here](https://i.sstatic.net/RiSOR.png)](https://i.sstatic.net/RiSOR.png)
>
> then further simplified to「于」. The original sense of the wind instrument is now written「竽」after「于」became extensively used for its grammatical function meaning and had lost its original meaning.
>
> # Glyph origin of 於
>
> 「於」and「烏」were originally the same character, but have been graphically differentiated. For reference, their development looked something like
>
> [![enter image description here](https://i.sstatic.net/arG0a.png)](https://i.sstatic.net/arG0a.png)
> [![enter image description here](https://i.sstatic.net/oGK75.png)](https://i.sstatic.net/oGK75.png)
>
> There was absolutely no difference between the characters「於」and「烏」before the Qin dynasty, and「烏/於」was used for its current grammatical function long before they became different characters.

---

The historical usage of「于」and「於」goes in accordance to something like the following timeline:

* Western Zhou

  + Only「于」is used for the grammatical function.
  + During the same period,「於」is used as an exclamation.
  + This is especially obvious when both「于」and「於」appear simultaneously: [![enter image description here](https://i.sstatic.net/SPP6X.png)](https://i.sstatic.net/SPP6X.png)
* Late Western Zhou to end of the Spring and Autumn period:

  + 「于」sees an additional use of a filler syllable to match rhythms across commonly used phrases.
  + 「於」gains the grammatical function of what was previously「于」, but「于」still sees higher usage frequency for this function, and there is no difference between the two in this context.
  + 「於」still kept its previous meaning (as an exclamation).
* Warring States and later:
  + 「於」overtakes「于」in frequency in the grammatical function sense, but both were still used and neither was permanently dropped.

See also [從“于 / 於”用法上的變化看複合詞“於是”的產生](http://www.cuhk.edu.hk/ics/clrc/crcl_94_1/yang.pdf).

---

\*There are differences between「于」and「於」when they're not used in the grammatical function sense, which this answer touches upon but doesn't explain thoroughly - detailed dictionaries will provide a more comprehensive explanation.


---

