Final answer:
The overlapping of cranial bones under the pressures of labor is called molding, which is aided by the fontanelles in newborns allowing the bones to overlap slightly to pass through the pelvis during birth.
Step-by-step explanation:
The term for the overlapping of cranial bones under the pressure of labor and the constraints of the pelvis is molding. This is a process that occurs naturally during childbirth to allow the infant's head to pass through the birth canal more easily. The areas of connective tissue between the cranial bones in newborns, known as fontanelles, permit this flexibility. These fontanelles enable the bones to push closer together or overlap slightly without causing harm. This should not be confused with craniosynostosis, a condition where there is a premature fusion of cranial sutures, affecting skull and brain growth.