Why 不便 instead of 不便利?


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.




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](https://japanese.stackexchange.com/q/24376/5010) 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.




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](https://japanese.stackexchange.com/q/24376/5010) 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.

