入る

From older 這い入る (haiiru, older pronunciation faiiru), itself a compound of 這い (“to crawl”, continuative form) +‎ 入る (iru, “to enter, to go in”).^[1][2][3][4]

• /faiiru/ → /fairu/ → /hairu/

This shortened hairu form is first attested from the early 1200s.^[1]

• (Tokyo) はいる [háꜜìrù] (Atamadaka – [1])^[3][4][5][1]
• IPA^(key): [ha̠iɾɯ̟]

• (Kyoto) はいる [hàìrú] (Teiki – [0])^[1]

入(はい)る • (hairu) intransitive godan (stem 入(はい)り (hairi), past 入(はい)った (haitta))

1. [from early 1200s] to enter, go into, get into a place or a thing

   お風(ふ)呂(ろ)に入(はい)る

   o-furo ni hairu

   get in the bath

   対(たい)策(さく)の検(けん)討(とう)に入(はい)る

   taisaku no kentō ni hairu

   enter countermeasure discussion → start discussing plans for countermeasures

   亀(き)裂(れつ)が入(はい)ったタイヤ

   kiretsu ga haitta taiya

   tire with cracks that have entered it → a cracked tire

   Antonym: 出る (deru, “to leave, to exit, to go out”)

   1. [from early 1900s] to join a group or organization
2. [from late 1700s] to be contained (in), to be included (in)
   • 2007, 新時代日漢辭典／新时代日汉辞典 (Xīn Shídài Rì-hàn Cídiǎn), 1st edition, 大新書局／大新书局 (Dàxīn Shūjú), →ISBN:

     旅(りょ)費(ひ)には朝(あさ)晩(ばん)の食(しょく)事(じ)代(だい)も入(はい)っています。

     Ryohi ni wa asaban no shokujidai mo haitte imasu.

     The morning and evening meal plans are also included in the travel expenses.

3. to be a member of a group, set, category

   先(せん)生(せい)、バナナはおやつに入(はい)りますか？

   Sensei, banana wa o-yatsu ni hairimasu ka?

   Teacher, do bananas count as snacks? (rhetorical question in popular culture)

4. to be in a container, building, etc.
   • 2007, 新時代日漢辭典／新时代日汉辞典 (Xīn Shídài Rì-hàn Cídiǎn), 1st edition, 大新書局／大新书局 (Dàxīn Shūjú), →ISBN:

     この部(へ)屋(や)には百(ひゃく)人(にん)入(はい)れる。

     Kono heya ni wa hyaku-nin haireru.

     In this room, one hundred people can enter → This room can contain a hundred people.

5. [from 1869] to enter a period of time

   令(れい)和(わ)時(じ)代(だい)に入(はい)る、晩(ばん)に入(はい)る

   Reiwa jidai ni hairu, ban ni hairu

   to enter the Reiwa era, to enter into evening

6. [from 1902] to be included and available for use

   ノートに罫(けい)が入(はい)った

   nōto ni kei ga haitta

   in the notebook, lines are in it → the notebook has lines in it → the notebook has ruled pages

• 手(て)に入(はい)る (te ni hairu)

From Old Japanese. First attested in the Man'yōshū of 759.^[6]

For the development of the to be necessary sense, consider the English phrase to come into it in the sense to be a factor in something. In modern usage, this particular sense is more commonly spelled as 要る.

• (Tokyo) いる [ìrú] (Heiban – [0])^[3][4][5][6]
• IPA^(key): [iɾɯ̟]

• (Kyoto) いる [írú] (Kōki – [0])^[6]

入(い)る • (iru) intransitive godan (stem 入(い)り (iri), past 入(い)った (itta))

1. [from 759] to go in; to come in
   • 2007, 新時代日漢辭典／新时代日汉辞典 (Xīn Shídài Rì-hàn Cídiǎn), 1st edition, 大新書局／大新书局 (Dàxīn Shūjú), →ISBN:

     俺(おれ)の耳(みみ)に水(みず)が入(い)った

     Ore no mimi ni mizu ga itta

     Water went in my ear

2. [from 900s] 要る: to be necessary, to be required

   お金(かね)がいるね

   okane ga iru ne

   money comes into it → money is needed → you'll need money

• Mostly confined to fixed expressions and idioms.

• 気(き)に入(い)る (ki ni iru)
• 手(て)に入(い)る (te ni iru)

• 恐(おそ)れ入(い)る (osoreiru)

入(い)る • (iru) transitive ^†nidan

1. to put something into something else

• 入(い)れる (ireru, modern form)

• 2002, Ineko Kondō; Fumi Takano; Mary E Althaus; et. al., Shogakukan Progressive Japanese-English Dictionary, Third Edition, Tokyo: Shōgakukan, →ISBN.