It's likely a misspelling of "juvenile," which means:
* Relating to or characteristic of youth: This could refer to age, appearance, behavior, or mental development.
* Immature: This often implies a lack of seriousness, responsibility, or judgment.
* Childish: This suggests behavior or qualities that are typical of a child.
It's also possible that the word you were looking for is "juvenilescent," which means "becoming juvenile." However, this word is not commonly used.
If you can provide more context about where you encountered this word, I might be able to help you further.