jejune
1. [ adjective ] displaying or suggesting a lack of maturity
Synonyms: juvenile puerile adolescent
Examples:

"adolescent insecurity" "jejune responses to our problems" "their behavior was juvenile" "puerile jokes"

Related terms: immature
2. [ adjective ] lacking in nutritive value
Synonyms: insubstantial
Examples:

"the jejune diets of the very poor"

Related terms: unwholesome
3. [ adjective ] lacking interest or significance
Synonyms: insipid
Examples:

"an insipid personality" "jejune novel"

Related terms: uninteresting