Which is the most correct Kanji Compound equivalent to 'aji mumpung' or 'being opportunist'? (オポチュニスト、便乗主義者、日和見主義者、御都合主義者 and 利己主義者)


[![enter image description
here](https://i.stack.imgur.com/KMSRS.png)](https://i.stack.imgur.com/KMSRS.png)

[![enter image description
here](https://i.stack.imgur.com/RXP4I.png)](https://i.stack.imgur.com/RXP4I.png)

_Context:_

I read an article **[here](https://terumojapan.xsrv.jp/WorldBlog/?p=7424)**
and stumbled over an interesting kanji compound, i.e.: **便乗主義者** - or
**オポチュニスト** (according to **[this](http://www.ei-
navi.jp/dictionary/content/opportunist/)** )

> Meaning: しばしば倫理に反する手段で、可能性のある利益の状況で目前の利益を取るさま.

In Bahasa Indonesia, we have this term as ' **Aji mumpung** '.

> **Aji mumpung** : conditioning or 'using'/exploiting a situation or
> circumstance rendered for self-interest while holding an office/holding a
> position of power.
>
> **[Source](https://kbbi.kemdikbud.go.id/entri/aji%20mumpung) - in Bahasa
> Indonesia**

According to Google, an **opportunist** is:

> a person who exploits circumstances to gain immediate advantage rather than
> being guided by consistent principles or plans, which brings my question,
> **self-opportunist** -> a person who exploits circumstances to gain
> immediate advantage for self-interest.

I researched it for a bit: According to
**[Oxford](https://en.oxforddictionaries.com/definition/opportunist)** , an
**opportunist** is:

A person who takes advantage of opportunities as and when they arise,
regardless of planning or principle.

So, my question is:

>   1. Is this true, that **`オポチュニスト、便乗主義者`** carry negative nuance as in the
> 'Aji mumpung' or 'being opportunist'?
>
>   2. What is/are the difference(s) between: オポチュニスト、便乗主義者、日和見主義者、御都合主義者 and
> 利己主義者?
>
>

According to **[this](https://oshiete.goo.ne.jp/qa/8407528.html)** , the
difference is: ''**

>
> 保守的な事なかれ主義を日和見主義と言う。左翼的なものの回避、革新的、急進的なことを避けようとする態度をかつての全共闘世代は日和見主義と言った。そういう意味では、利己主義と同義。が、革新的変革によって、自己に利があると考えた場合、左翼思想こそが利己主義ということになる。

** Could someone confirm whether this is true? (please elaborate, if possible
a different usage example that denotes the differences). It seems that it's
used much more in politics, but can we say that in our daily live? (such as>
日和見主義の政治家)

> 3.Is there any `'daily word/daily set phrase(s) in Japanese'` comparable or
> at least means the same as **being opportunist** as in ' **Aji mumpung** '
> that has a **colloquial sense** ( _`ragam cakapan`_ )?




>   1. Is this true, that オポチュニスト、便乗主義者 carry negative nuance as in the 'Aji
> mumpung' or 'being opportunist'?
>

便乗主義者 clearly sounds negative and derogatory. (I know nothing about Bahasa
Indonesia.) オポチュニスト is a fairly rare loanword, but I see no reason why it's
different from English "opportunist".

>   2. What is/are the difference(s) between: オポチュニスト、便乗主義者、日和見主義者、御都合主義者 and
> 利己主義者?
>

I think 日和見主義者 is the primary word that corresponds to English "opportunist".
It should be on every dictionary. I'm not sure if 便乗主義者 is an established
word, although the meaning is straightforward. Using オポチュニスト is not
recommended unless you're talking to someone who is good at English.

御都合主義者 is almost the same as 日和見主義, but the former feels a little more
colloquial to me. In storytelling, 御都合主義 has another slangy meaning described
[here](https://dic.nicovideo.jp/a/%E3%81%94%E9%83%BD%E5%90%88%E4%B8%BB%E7%BE%A9).
利己主義 is a clearly different word meaning "egoism".

**EDIT** : Perhaps
[尻尾を振る](https://kotobank.jp/word/%E5%B0%BB%E5%B0%BE%E3%82%92%E6%8C%AF%E3%82%8B-521711)
is a more colloquial/slangy expression that can convey a similar idea.
[長いものには巻かれろ](https://www.weblio.jp/content/%E9%95%B7%E3%81%84%E7%89%A9%E3%81%AB%E3%81%AF%E5%B7%BB%E3%81%8B%E3%82%8C%E3%82%8D)
has a similar meaning but it kind of recommends opportunism.




>   1. Is this true, that オポチュニスト、便乗主義者 carry negative nuance as in the 'Aji
> mumpung' or 'being opportunist'?
>

便乗主義者 clearly sounds negative and derogatory. (I know nothing about Bahasa
Indonesia.) オポチュニスト is a fairly rare loanword, but I see no reason why it's
different from English "opportunist".

>   2. What is/are the difference(s) between: オポチュニスト、便乗主義者、日和見主義者、御都合主義者 and
> 利己主義者?
>

I think 日和見主義者 is the primary word that corresponds to English "opportunist".
It should be on every dictionary. I'm not sure if 便乗主義者 is an established
word, although the meaning is straightforward. Using オポチュニスト is not
recommended unless you're talking to someone who is good at English.

御都合主義者 is almost the same as 日和見主義, but the former feels a little more
colloquial to me. In storytelling, 御都合主義 has another slangy meaning described
[here](https://dic.nicovideo.jp/a/%E3%81%94%E9%83%BD%E5%90%88%E4%B8%BB%E7%BE%A9).
利己主義 is a clearly different word meaning "egoism".

**EDIT** : Perhaps
[尻尾を振る](https://kotobank.jp/word/%E5%B0%BB%E5%B0%BE%E3%82%92%E6%8C%AF%E3%82%8B-521711)
is a more colloquial/slangy expression that can convey a similar idea.
[長いものには巻かれろ](https://www.weblio.jp/content/%E9%95%B7%E3%81%84%E7%89%A9%E3%81%AB%E3%81%AF%E5%B7%BB%E3%81%8B%E3%82%8C%E3%82%8D)
has a similar meaning but it kind of recommends opportunism.

