When trying to write in Japanese, I often come across words that have multiple possible translations into Japanese, and am unsure which one to use. Though it is difficult to make any general rule over what word to pick (as there isn't an obvious basis of selection), one particular kind of choice that I often see is whether to use lexical or grammatical forms of expression (namely, to form 漢語 expressions by concatenating words or adding affixes, or to split off words and modify them with 文法). This boils down into three main questions, though any advice on this general topic is appreciated as well:

  1. When negating 漢語, is there a way to tell whether 「【無・不・非・未】〜」 or 「〜ない」is more commonplace/acceptable/appropriate.

  2. When using 漢語 to modify other 漢語 (e.g. with 「〜的(な)〜」), is there a rule for when to break off and start using particles/okurigana, and when to create a compound (possibly with rendaku) as might be seen with gerund (not sure if gerund really makes sense here, but nominalized verb in case that is clearer) suffixes such as「〜狩り」and 「〜作り」

  3. Is there a rule for determining whether certain jukugo or their naturally alternatives (「血色›血の色」、「天地›天と地」、「星学›天文学」)are more appropriate, or even when the 熟語 version is rare or obsolete

Examples (of the (1) and (2)):

  • 関係】vs.【関係ない・なし
  • 【宗教的意識】vs. 【宗教的意識】
  • 【ケーキ作り】vs. 【ケーキ作る(こと)】

2 Answers 2


Your question is too general and broad. There are rules of thumb but usually no written rules.

For 「【無・不・非・未】〜」 or 「〜ない」, 無 usually means ない(not exists), 不 usually means "not", 非 usually means "other than", and 未 usually means "not yet/completed"

For 【関係ない・なし】【宗教的な意識】vs. 【宗教的意識】, without 送り仮名, usually it tends to sound like a term, and with 仮名 you can add an extra feel or nuance to it.

For 3, some words are dialectal/archaic/rare and some words are specific terms which can't be replaced by other "equivalent" compound/word(e.g. 血色 vs.血の色).

  • I might have been poor at explaining the first category; I know the meanings of the four negative prefixes, my question was whether there was a rule as to when to use the appropriate one or to perform grammatical negation using the appropriate stem and -ない Commented May 18, 2017 at 0:10
  • You mean something like 不許可 vs. 許可しない(事), 非公開, vs. 公開していない, 未解決 vs. 解決していない? As I said it depends on the context, which one the speaker favors, or some compounds are just terms which you can not replace with other "equivalent" expression.
    – someone
    Commented May 18, 2017 at 0:25

Your question is too general and broad as is said in someone's answer, so I am going to answer your question only on how to use the prefixal kanjis 無/不/非/未 adding the meaning of negation to the following kanji word.

There are a lot of similar questions on the Internet because the question you posted is also difficult even to Japanese. So I understand it is a much more difficult problem for non-native Japanese learners who does not have enough vocabulary. I would not like to say, because there is not a general rule for it, it is the only way that you should learn it one by one to learn the use of them.

After I examined some pairs of answer and question on the Internet that is similar to your question closely, and I extracted some of the answers that I judged to be easy to understand and show you them as follows:

未{み} is read 未{いま}だ~せず, which means "it is not yet ...". 未 is used for the thing which has not come out or realized yet, but its realization is possible in the future.

Examples: 未完成{みかんせい}(未{いま}だ完成{かんせい}せず。 it is not yet completed



無{む} is read ~なし, which means "there isn't ...", "there's nothing of ..." or "... doesn't exist".

Examples: 無{む}関心{かんしん}(関心{かんしん}がない。unconcerned or there is not concern to)、 無{む}気{き}力{りょく}(気{き}力{りょく}がない。There is not willpower.


Basically, and have the same meaning. As for their difference, 不 is used to negate a declinable word (verb / adjective / adjectival noun), and 非 is used to negate an indeclinable word (noun / pronoun).
So 不{ふ} is read ~せず meaning "do not" or "not", and 非{ひ} is read ~にあらず meaning "non-".



Examples:非{ひ}常口{じょうぐち}(常{つね}の口{くち}にあらず。 an emergency exit, literally not a usual exit


Difference between 不用 and 不要
Whether it is useful/worthy or not: 不用{ふよう}⇔入用{にゅうよう}/入用{いりよう}
Whether it is necessary or not: 不要{ふよう}/不必要{ふひつよう}⇔必要{ひつよう}


  • 1
    Regrettably, there was a bit of ambiguity in my question which lead to this misunderstanding. I was not asking "how do I use/pick 無・非・不・未", it was "when do I use 無~ as opposed to ~無し" and so forth. Thanks for the detailed and informative answer in any case. I was wondering what the distinction between 非 and 不 was in any case, so you answered at least that. Commented May 23, 2017 at 2:18
  • @archaephyrryx: I'm sorry about my misunderstanding to your question. But I'm glad that the information about the difference between 非 and 不 could be of some help to you. I would proudly say the examples I showed you are fine selections from my kanji-Japanese dictionary; the selected words would cover almost all the common use except for advanced one.
    – user20624
    Commented May 23, 2017 at 4:02

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