<p><strong>Adjective</strong></p><ul><li>of, pertaining to, characteristic of, or suitable or intended for young persons: juvenile books.</li><li>young; youthful: juvenile years.</li><li>immature; childish; infantile: His juvenile tantrums are not in keeping with his age.</li></ul><p><strong>Noun</strong></p><ul><li>a young person; youth.</li><li>Theater. a youthful male or female role.</li><li>an actor or actress who plays such parts.</li><li>a book for children.</li><li>Ornithology. a young bird that has its first set of contour feathers.</li><li>a two-year-old racehorse.</li></ul>