Translation guide
The English word 'adult' can refer to a grown person, mature behavior, or content intended for adults. In Japanese, the most common equivalent is 大人 (otona), but other expressions exist depending on context, such as legal adulthood or formality.
Referring to a person who is fully grown, not a child.
The standard, neutral word for an adult person. Used in everyday conversation.
He is already an adult.
What do you want to be when you grow up?
Refers to a person who has reached the legal age of adulthood (20 in Japan, though lowered to 18 in 2022). More formal than 大人.
Literally 'adult person'. Used when you need to be explicit, but 大人 alone is usually sufficient.
An adult helped me.
Describing actions or attitudes that are mature, not childish.
Can also mean 'mature' when describing behavior. Often used in phrases like 大人げない (immature).
Referring to media, entertainment, or topics intended for adults only, often sexual or explicit.
Means 'for adults' or 'adult-oriented'. Used for movies, books, etc. that are not suitable for children.
Referring to the state of being legally recognized as an adult.
Legal term for adulthood, as in 'age of majority'. Used in phrases like 成年年齢 (legal adult age).
アダルト is almost exclusively used for sexual or pornographic content. To refer to a grown person, always use 大人.
大人 is the everyday word for an adult person. 成人 is more formal and often used in legal or official contexts, such as 成人式 (coming-of-age ceremony) or 成人年齢 (legal adult age).
日本では18歳で成人になります。
In Japan, you become an adult at 18.
To act like an adult / handle things maturely.
He is childish/immature.
Means 'mature' in a psychological or emotional sense. More formal/literary.
He has a mature way of thinking.
This movie is for adults.
Loanword from English, often used for 'adult' in the sense of pornographic or explicit content.
This word strongly implies sexual content. Use 大人向け for general 'not for children'.
Adult website
Similar to 大人向け but more formal, often used in legal or official contexts.
Adult magazine
The age of majority is 18.