How to say "adult" in Japanese

• 大人おとなJLPT N5approx.Common
  no-adjective, na-adjectiveThe everyday word for an adult person as opposed to a child; it is the natural choice when talking about people, as in speaking of adults and children.
  大人おとなだけこの映画えいがが見みえる。↗

  Only adults can see this film.
• 成人せいじんJLPT N3approx.Common
  nounA word for a person who has reached adulthood, typical of official, legal, or medical contexts; in casual conversation about people, 大人 is the usual choice.
  その映画えいがは成人せいじんしかみられない。↗

  Only adults may watch that film.
• アダルトCommon
  na-adjective, nounThe loanword, used almost entirely for adult entertainment and adult content of a sexual nature; it is seldom the word you want for an adult person.
• 成虫せいちゅうCommon
  nounThe term for the adult stage of an insect, corresponding to 'imago'; it belongs to biological description of insect life stages and is never used of people.
  その虫むしはさなぎから成虫せいちゅうになった。↗

  The insect grew out of a pupa into an imago.
• 大人っぽいおとなっぽいCommon
  i-adjectiveAn adjective describing manner, appearance, or behavior that seems grown-up or mature; it characterizes someone as adult-like rather than simply stating that they are an adult.

大人 is the everyday word for an adult person, 成人 the formal one for official or legal contexts, 「アダルト」 belongs to adult entertainment, 成虫 means an adult insect, and 「大人っぽい」 describes grown-up manner or maturity.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 大人おとなadult
• 成人せいじんadult
• アダルトadult
• 成虫せいちゅうimago
• 大人っぽいおとなっぽいgrown-up (manner, etc.)
• 大人だいにんadult
• 一丁前いっちょうまえadult
• 成体せいたいadult
• 丁年者ていねんしゃadult
• 成年者せいねんしゃadult
• アダルティadult
• いっちょまえadult
• 成人向けせいじんむけadult (film, etc.)
• アダルティックadult
• 親虫おやむしimago
• 一人前いちにんまえadult
• 大人たいじんadult
• 人数ひとかず(being counted as an) adult
• ひとadult