What are the differences among the following two-kanji words that seem to mean
"eternity":

  * 永遠 {えいえん}
  * 永久 {とわ}
  * 永世 {えいせい}
  * 永代 {えいたい}
  * 永劫 {えいごう}
  * 永永 {えいえい}
  * 久遠 {きゅうえん}
  * 悠久 {ゆうきゅう}
  * 恒久 {こうきゅう}
  * 恒常 {こうじょう}
  * 長久 {ちょうきゅう}
  * 無窮 {むきゅう}

Please include any other related words (preferably two-kanji only) but please
exclude those that make use of period of a lifetime like 一生, 末代 etc, or big
number of years/era like 千代, 万古 etc.

p/s: I noticed that the first two 永遠 and 永久 are the most commonly used; is it
true and why them instead of the others?
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2011-09-11T15:37:12.927
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2012-07-30T13:31:05.113
2011-09-11T15:53:38.000
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question
vocabulary nuances synonyms definitions
Fun with synonyms - "eternity"
1. 永遠{えいえん}

> [彼女]{かのじょ}は[夫]{おっと}を永遠に[愛]{あい}し[続]{つづ}けるであろう。  
>  I don't think she'll ever get sick of that guy (her husband).

  2. 永久{えいきゅう} 

> 私はこの[出来事]{できごと}を永久に[忘]{わす}れない。  
>  I wont forget this.

  3. 永世{えいせい} 

> 永世[中立国]{ちゅうりつこく}  
>  A Neutral Country (in Japanese without the word eisei it is not implied
> that a country has a policy of neutrality. Whereas, in English, the word
> Neutral Country by itself implies that this is a policy that the country has
> singed onto. The eisei portion of this word makes the idea a unchangeable
> bound policy.)

  4. 永代{えいたい} 

> pronounced eidai and this is used as a name of a person or place. There is a
> city in Tokyo called Eidai and a bridge called Eidai-bashi

  5. 永劫{えいごう} 

> 永劫[回帰]{かいき}  
>  An ancient Greek philosophy called "Eternal Recurrence", which is also
> found in ideas like Reincarnation and the circle of life ideas, where life
> never dies, it just changes or revolves.

  6. 永永{えいえい} 

> 永永[無窮]{むきゅう}の毎日  
>  "Same old same old" might be a good definition for the idea that there was
> nothing new that week and every day was kinda the same, unchanging.

  7. 久遠{きゅうえん}

> Pronounced Ku-On and used in people's names

  8. 悠久{ゆうきゅう} 

> Sometimes written UQ and found in Game Titles but has the same meaning as
> Eien 永遠 except used for game or book or movie titles.

  9. 恒久{こうきゅう}

> 恒久的{こうきゅうてき}な平和など[幻想]{げんそう}に過ぎない。  
>  A world without war is a pipe dream. (in Japanese uninterrupted peace means
> a world without war)

  10. 恒常{こうじょう} 

> イングランドとスコットランドの間の[恒常的]{こうじょうてき}な[国境]{こっきょう}[戦争]{せんそう}は終わった。  
>  The constant border wars between England and Scotland finally came to an
> end.

  11. 長久{ちょうきゅう}

> The name of the Japanese "Chokyu Era"

  12. 無窮{むきゅう} (see number 6)
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2011-09-24T06:10:36.650
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2011-11-07T14:06:21.930
2011-11-07T14:06:21.930
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answer
There's a lot of good information in the other answer already, the main goal
of this answer is to fill in some of the other definitions etc.

  * 永遠{えいえん}:

> When something continues for all time in a certain state without ending, for
> example love which never ends or neverending world peace. `永遠に` can take the
> meaning of "forever" or less commonly "permanently". Highly interchangeable
> with `永久{えいきゅう}` and vice-versa.

  * 永久{えいきゅう}: 

> Something which is permanent or perpetual, for example permanent love or a
> permanent license. Also used for immortal achievements, works, fame etc.
> `永久に` can take the meaning of "permanently" or less commonly "forever".  
>  
>  Usually `えいきゅう`, but can also be pronounced `えいこう`. Is sometimes pronounced
> `とわ` to take a more abstract meaning, but the Kanji `常{とわ}` is more common
> with that reading according to Daijirin.

  * 永世{えいせい}: 

> A long period of months and years or an era which never ends. Also used in
> `永世[中立国]{ちゅうりつこく}` as Joshua has noted.

  * 永劫{えいごう}: 

> An eon. (The other answer has already done a great job explaining about
> 永劫[回帰]{かいき} I think.)

  * 永代{えいたい}: 

> A very long time in months/years or eternity. Used in `永代[供養]{くよう}`,
> "services performed in perpetuity by a Buddhist temple for the repose of a
> departed soul" according to JMDict.

  * [永々]{えいえい}: 

> I think this can mean "forever", but it generally just emphasizes a notably
> long period of time, e.g. "the practice has continued for 100 years."
> Usually written with a `くりかえし` (`々`) but can also be written as `永永`.

  * 久遠{くおん}: 

> A buddhist term for eternity. Infinite time or the distant past/distant
> future. Usually pronounced `くおん` but can also be `きゅうえん`.

  * 悠久{ゆうきゅう}: 

> Unending. Used in `悠久の[歴史]{れきし}` (neverending history.)

  * 恒久{こうきゅう}: 

> Used in permanent government/constitutions/laws/treaties/measures/solutions
> et al.

  * 恒常{こうじょう}: 

> Doesn't really mean "eternal" so much as "constant", e.g. "constant
> weather".

  * 長久{ちょうきゅう}: 

> Used in wars/battles to indicate eternal luck/good fortune e.g.
> `[武運]{ぶうん}長久` and `幸運{こううん}長久`. Also indicates the Choukyuu era from
> 10/11/1040-24/11/1044 as has been noted.

  * 無窮{むきゅう}: 

> Something which is always in a state which never changes, e.g. "an
> unchanging art style" or something which is of the state of being
> infinite/immortal.
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2011-11-08T06:55:16.287
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2011-11-09T05:55:48.063
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answer
I'd like to add: 無限{むげん}. It means infinity but infinity and eternity can be
interchangeable at times..
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2012-07-30T13:31:05.113
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