開く・空く・明く|あくaku[2]odaka (tail-high)
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Which spelling to use
開く開く（あく） is the most common written form for this verb and the recommended default for beginners; it uses kanji and kana together.
空く空く（あく） is less common than 開く（あく） as a written form of this verb; it also uses kanji and kana together.
明く明く（あく） is the least common of these written forms for this verb and also uses kanji and kana together.
Definitions
- godan verb, intransitive verbto open (e.g. doors)esp. 開く
- godan verb, intransitive verbto open (e.g. business, etc.)esp. 開く
- godan verb, intransitive verbto be emptyesp. 空く
- godan verb, intransitive verbto be vacant; to be available; to be freeesp. 空く
- godan verb, intransitive verbto be open (e.g. neckline, etc.)esp. 明く
- godan verb, intransitive verbto have been opened (of one's eyes, mouth, etc.)esp. 明く
- godan verb, intransitive verbto come to an endesp. 明く
- godan verb, transitive verbto open (one's eyes, mouth, etc.)esp. 明く
- godan verb, intransitive verbto have a hole; to form a gap; to have an interval (between events)
Conjugation
| Dictionary form | 開く（あく） |
|---|---|
| Polite (masu) | 開きます（あきます） |
| Negative (nai) | 開かない（あかない） |
| polite (masen) | 開きません（あきません） |
| classical zu / nu | 開かず・開かぬ（あかず・あかぬ） |
| Past (ta) | 開いた（あいた） |
| polite (mashita) | 開きました（あきました） |
| Past negative (nakatta) | 開かなかった（あかなかった） |
| polite (masen deshita) | 開きませんでした（あきませんでした） |
| Te form | 開いて（あいて） |
| Potential | 開ける（あける） |
| Passive | 開かれる（あかれる） |
| Causative | 開かせる（あかせる） |
| Causative passive | 開かせられる・開かされる（あかせられる・あかされる） |
| Conditional (ba) | 開けば（あけば） |
| tara | 開いたら（あいたら） |
| Volitional | 開こう（あこう） |
| polite (mashou) | 開きましょう（あきましょう） |
| Imperative | 開け（あけ） |
Common forms generated by rule; see the senses for honorific or irregular usage.
Transitive / intransitive pair
ドアが開く
ドアを開ける
開く (intransitive) describes something coming open on its own, while 開ける (transitive) describes an agent deliberately opening something.
ドアが開く
ドアを開く
開く used intransitively (あく) emphasizes the resulting open state, whereas 開く used transitively (ひらく) emphasizes the action of opening, often suggesting unfolding or spreading apart.
Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only
Synonyms & antonyms
- SynonymオープンNeutralA loanword for opening for business or opening up, used mostly of stores and facilities, as in 「新店がオープンする」; 「開く」 also covers doors and the like opening.
- Antonym閉じるとじるNeutralThe opposite of 「開く」: to close or shut, as in 「目を閉じる」.
For doors or shops standing open, 「開く」 is the default. A store or facility opening is typically 「オープン」, and for closing use 「閉まる」 or 「閉じる」.
Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only
Japanese definitions
Kanji in this word
English equivalents
See also
