Young; not fully developed. / Characteristic of youth or immaturity; childish.

A prepubescent child. / A person younger than the age of majority; a minor.

plural of juvenile

juvenility

In a juvenile manner.

The state or quality of being juvenile. / juvenile behaviour, writing, etc.

plural of juvenilization

The act or process of juvenilizing. / The retention, by adults in a species, of traits previously seen only in juveniles.

simple past tense and past participle of juvenilize

present participle of juvenilize