1.
adult
A person who has reached the age of majority.
成人向けの映画だ。
This is a movie for adults.
お酒は成人しか買えない。
Only adults can buy alcohol.
成人の数は年々減っている。
The number of adults is decreasing year by year.
2.
coming of age
The process or event of reaching adulthood.
成人式に参加した。
I attended the coming-of-age ceremony.
日本では十八歳で成人になる。
In Japan, you become an adult at 18.
成人の日には、多くの若者が着物を着て写真を撮る。
On Coming of Age Day, many young people wear kimono and take photos.
成人 refers to adults and the process of becoming an adult.
CULTURAL NOTE:
成人の日 (Coming of Age Day) is a national holiday in Japan held on the second Monday of January. Young people who turned 20 (or now 18, after the 2022 law change) during the year celebrate with ceremonies and often wear traditional clothing.
COMMON COLLOCATIONS:
- 成人式 (coming-of-age ceremony)
- 成人の日 (Coming of Age Day)
- 成人向け (for adults)
- 成人病 (adult diseases/lifestyle diseases)
- 成人年齢 (age of majority)
SIMILAR WORDS:
- 成人: adult (legal/formal sense)
- 大人: adult (general, everyday)
- 成年: age of majority (more legal/formal)