immature

adjective

1. 1

   (of birds) not yet having developed feathers

   a small unfledged sparrow on the window sill

2. 2

   not yet mature

3. 3

   characteristic of a lack of maturity

   immature behavior

4. 4

   not fully developed or mature; not ripe

   unripe fruit

   fried green tomatoes

5. 5

   (used of living things especially persons) in an early period of life or development or growth

   young people