How are the suffixes ーまる and ーめる used?


Recently I came across the word 狭める, "to narrow" or "to make narrow." I
wondered about its relation to 狭い and then I found some other similar
adjective-verb pairs:

  * 固い ー 固める
  * 高い ー 高める
  * 深い ー 深まる

I'm curious if this is a common way to turn adjectives (it seems like only
い-adjectives) into verbs. Also, is it an alternative to the adverbial form +
なる and the adverbial form + する？




It seems that only a small subset of い-adjectives can be turned into verbs by
using suffixes -まる and -める.

-める generates a transitive verb and -まる an intransitive verb.

So, for a single い-adjective, both -める and -まる verbs may exist:

  * 深める: to make deep
  * 深まる: to become deep

For some い-adjectives, only -める verbs are valid:

  * × 苦しまる, ○ 苦しめる
  * × 痛まる, ○ 痛める

And there are many い-adjectives that do not have -まる/-める verbs.

  * × 大きまる, ×大きめる
  * × 嬉しまる, ×嬉しめる

As you mentioned, it is almost equivalent in meaning to 〜くする and 〜くなる
respectively. For example, 深まる≒深くなる and 深める≒深くする. But they are not always
interchangeable and their usage may be difficult, as described in [this
article](http://nihonngokyoushi-naniwanikki.blog.jp/archives/61766668.html).

[This
book](https://books.google.co.jp/books?id=l-C4H2sBJlEC&printsec=frontcover&hl=ja#v=onepage&q&f=false)
is describing the differences between -まる/-める verbs and -くなる/-くする in p.401:

>
> 「〜くなる」「〜くする」は形容詞の表す程度がより甚だしくなる（する）ことを表しますが、「〜まる」「〜める」は形容詞の表す状態への変化を表します。ただし厳密には区別されない場合もあります。




It seems that only a small subset of い-adjectives can be turned into verbs by
using suffixes -まる and -める.

-める generates a transitive verb and -まる an intransitive verb.

So, for a single い-adjective, both -める and -まる verbs may exist:

  * 深める: to make deep
  * 深まる: to become deep

For some い-adjectives, only -める verbs are valid:

  * × 苦しまる, ○ 苦しめる
  * × 痛まる, ○ 痛める

And there are many い-adjectives that do not have -まる/-める verbs.

  * × 大きまる, ×大きめる
  * × 嬉しまる, ×嬉しめる

As you mentioned, it is almost equivalent in meaning to 〜くする and 〜くなる
respectively. For example, 深まる≒深くなる and 深める≒深くする. But they are not always
interchangeable and their usage may be difficult, as described in [this
article](http://nihonngokyoushi-naniwanikki.blog.jp/archives/61766668.html).

[This
book](https://books.google.co.jp/books?id=l-C4H2sBJlEC&printsec=frontcover&hl=ja#v=onepage&q&f=false)
is describing the differences between -まる/-める verbs and -くなる/-くする in p.401:

>
> 「〜くなる」「〜くする」は形容詞の表す程度がより甚だしくなる（する）ことを表しますが、「〜まる」「〜める」は形容詞の表す状態への変化を表します。ただし厳密には区別されない場合もあります。

