1. (adjective) displaying or suggesting a lack of maturity

• adolescent
• jejune
• juvenile

1. (adjective) displaying or suggesting a lack of maturity

• immature

1. (adjective) of or characteristic of a child

• childishness
• puerility

2. (adjective) displaying or suggesting a lack of maturity

• callowness
• callowness
• jejuneness
• jejuneness
• juvenility
• juvenility
• childhood
• puerility
• jejuneness
• jejunity
• tameness
• vapidity
• vapidness

1. (adjective) of or characteristic of a child

• child
• kid