This is another term used for the process of development of a baby's body inside the mother's uterus. It is different to proximodistal. It means that the baby's head is developed first, and then the other parts are developed. It means, development from "top to bottom".
Cephalocaudal development is a motor development which occurs in the first two years of life and examples of Cepalocaudal are head before arms and trunk, arms and trunk before legs.
Simply put it means that the order of development is from top to bottom, head to foot. Motor nerve development in this way ensures that the brain is formed first.