undevelopedbody

2. A body that is not yet strong or complete in its shape.

The tadpole's undeveloped body slowly changed into a frog's body.

3. A body that has not been trained or built up.

After months of rest, he returned with an undeveloped body and weak muscles.

4. A body in an early stage of growth before adult features appear.

Scientists studied the undeveloped body of the insect to learn how it grows.