ら抜き言葉

In Japanese, ra-nuki kotoba ら抜き言葉, "ら-removed speech," refers to a way of talking that omits the ra ら in the potential form of ichidan 一段 verbs, conjugating them like godan 五段 verbs that end in ru る.

For example: tabereru 食べれる is taberareru 食べられる, "able to eat," with the ra ら removed.

• Explanation
• Passive Form

Explanation

Usually contractions are made from saying things too fast, however, in the case of ra-nuki kotoba, it's thought that the removal of the ra ら comes from conjugating the verb wrongly, rather than too quickly.^{[ら抜き言葉 - 大辞林 第三版 via kotobank.jp, accessed 2019-07-15]}

To understand this, a bit of background about Japanese verbs is necessary.

The godan 五段 verbs are verbs that can change their ending to "five," go 五, different vowels depending on how they're conjugated. For example:

• kaka-nai 書かない
  To not write.
• kake-ru 書ける
  To be able to write.
• kaki 書き
  Writing.
• kako-u 書こう
  Let's write.
• kaku 書く
  To write.

By contrast, the ichidan 一段 verbs that keep the same ending no matter how they're conjugated. This happens because, instead of changing the vowel of the last syllable, ichidan verbs simply remove the last syllable altogether.

• tabenai 食べない
  To not eat.
• taberareru 食べられる
  To be able to eat.
• tabe 食べ
  Eating.
• tabeyou 食べよう
  Let's eat.
• taberu 食べる
  To eat.

In the case above, taberu is the base form, and you can achieve any other form by removing the ru and replacing it with something else.

All ichidan verbs end with either ~eru or ~iru. In other words, they always end with ~ru. On the other hand, godan verbs can end with ~u, ~ku, ~su, ~tsu, ~nu, ~bu, ~mu, and ~ru.

Suffice to say that most verbs are godan verbs.

Here's a comparison between "to cut," kiru 切る (godan) and "to wear," kiru 着る (ichidan).

• kiranai 切らない
  kinai 着ない
  To not cut, wear.
• kireru 切れる
  kirareru 着られる
  To be able to cut, wear.
• kiri 切り
  ki 着
  Cutting, wearing.
• kirou 切ろう
  kiyou 着よう
  Let's cut, wear.
• kiru 切る
  kiru 着る
  To cut, wear.

So, as you can see, although the base form is pretty much the same, basically everything else is different.

It's common enough to say kireru 着れる instead of kirareru 着られる that it even has an entry in the dictionary.^{[着れる - デジタル大辞泉 via kotobank.jp, accessed 2019-07-21]}

However, the correct way is kirareru. The kireru, without ra, is grammatically incorrect.^{[動詞(9)可能動詞 - kokugobunpou.com, accessed 2019-07-21]}

In other words, the ra-nuki kotoba, which are common both in Real Life and in anime, are all grammatically incorrect. You may hear it, you may even end up using it, but beware that the proper way conjugating the ichidan verbs to the potential is with rareru, and not with just reru.

Passive Form

Note that the ra-nuki kotoba affects only the potential form and not the passive form of verbs. To elaborate:

• kireru 切れる
  kirareru 着られる
  To be able to cut, wear.
• kirareru 切られる
  kirareru 着られる
  To be cut, worn by.

With godan verbs, the passive and potential forms are different: kireru vs. kirareru. However, with ichidan verbs, the passive and potential forms are identical: kirareru vs. kirareru..

Since you can remove the ra from the potential kirareru, it would make sense that you could do the same with the passive kirareru, given that they are identical.

However, the ra-nuki kotoba aren't mere contractions. They are, again, conjugating an ichidan verb like a godan verb.

Since with godan verbs the potential form doesn't have the ra, the ra is removed from the potential form of ichidan verbs. In the passive form, the godan verb DOES have the ra, so you don't need to remove it from ichidan verbs, because it's already the same.