Is there a grammatical (or semantic) reason that explains why the opposite of 便利(な) is 不便(な)rather than 不便利(な)。 I'm asking because I noticed a similar thing possibly occurring with 満足 and 不満 and was wondering if there was some underlying information that could help me better understand Japanese grammar.

1 Answer 1


Many on-yomi kanji compounds were made by combining two kanji with similar meanings.

  • 満足: 満 ≒ 足 ≒ suffice; satisfy
  • 便利: 便 ≒ 利 ≒ convenience; advantage
  • 明瞭: 明 ≒ 瞭 ≒ clear; visible

This is because the on-reading of each kanji is very short and people needed two kanji to disambiguate. For example, マン by itself is too ambiguous because it can mean ten thousand (万), chronic (慢), etc.

But if you add 不, two kanji is often long enough and you may no longer have to say two similar kanji. There is no such word as [*]不万 (non-ten-thousand?), [*]不慢 (non-chronic?), [*]不勉 (non-study?) or [*]不弁 (non-valve?).

  • 不満
  • 不便

For some compounds, you cannot omit kanji at all (eg 不連続, 不確実). Or omitting one kanji may change the meaning a bit (eg 不明 = unknown vs. 不明瞭 = obscure). Basically you'll have to memorize each word individually.

  • Thanks for the answer as always. One follow-up. I understand that affixes are very much a case-by-case subject and applying rules to them might be a losing battle and I'm not trying to look for shortcuts but I wonder, are 不便利 and 不満足 categorically wrong? They're obviously not in common use (if at all) but if you heard them, would your native ears understand?
    – G-Cam
    Commented May 23, 2017 at 16:49
  • 2
    @G-Cam 不満足 is less common but actually in use. 不満 also means complaint rather than dissatisfied. 不便利 is not used but at least we can understand :-)
    – naruto
    Commented May 24, 2017 at 1:45

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