<p><strong>Adjective</strong></p><ul><li>Characteristic of or befitting an infant; babyish; childish: infantile behavior.</li><li>Synonyms: weak, immature, puerile.</li><li>Antonyms: mature, adult.</li><li>Of or relating to infants or infancy: infantile diseases.</li><li>Physical Geography: youthful.</li></ul>