自動詞（じどうし、jidoushi）
- intransitive verb

The Japanese word 自動詞 (じどうし, jidōshi) refers to an intransitive verb. Intransitive verbs are verbs that do not take a direct object. They express an action or state of being performed by the subject, and the action does not directly affect anything else in the sentence. Essentially, the action "stays" within the subject. This contrasts with transitive verbs, which require a direct object to receive the action.

⚫︎ドアが開きます。 Translation: The door opens. ⚫︎子供が寝ます。 Translation: The child sleeps. ⚫︎雨が降ります。 Translation: It rains.

You use 自動詞 to describe actions or states where the subject is the one performing the action, and nothing else is directly impacted by that action. It's crucial to understand the difference between 自動詞 and transitive verbs (他動詞, tadoushi) to form grammatically correct sentences in Japanese. When you see a verb, consider whether it needs an object to complete its meaning. If it doesn't, it is likely a 自動詞.

自動詞 is written with the kanji 自 (ji - self), 動 (dō - move), and 詞 (shi - word). The reading is typically written in hiragana as じどうし. There is no other common way to write this word. The okurigana (送りがな - suffix hiragana) for individual verbs will vary depending on the specific 自動詞. For example, the okurigana for 開きます is き (ki), for 寝ます is ます (masu).

There are no direct synonyms for 自動詞, as it is a grammatical term. The concept, however, can be contrasted with the concept of a transitive verb.

The antonym of 自動詞 is 他動詞 (たどうし, tadōshi), which means transitive verb.

電車が駅に着きました。 ・Translation: The train arrived at the station. ・Explanation: The subject, the train, is performing the action of arriving. The station is where it arrives, not what it acts upon. Therefore, 着きます is a 自動詞.

風が吹きます。 ・Translation: The wind blows. ・Explanation: The wind (subject) is doing the action of blowing, the action doesn't act upon something else directly, so this is an example of an intransitive verb or 自動詞.

The word 自動詞 is a compound word. 自 (ji) means "self" or "oneself". 動 (dō) means "motion" or "movement". 詞 (shi) means "word" or "verb". So, the word literally means "self-moving verb", which perfectly describes its function: a verb that describes an action done by itself, without acting on an object.