adjective

1. 1. young or youthful
   2. immature or childish
2. of, characteristic of, or suitable for children or young persons
3. Geol. emanating from the interior of the earth for the first time: said of gas, water, etc.

Etymology: L juvenilis < juvenis, young

noun

1. a young person; child or youth
2. an actor who plays youthful roles
3. ☆ a book for young people
4. a two-year-old race horse
5. Biol. a young plant or animal differing variously in form, features, etc. from the adult