What is the definition or description of: large head?

Macrocephaly: Large heads in infancy need to be followed by pedi MD over time. By itself, can be due to parental large head. If it is out of range and no family history and other things are occurring, i.e. delayed speech and behaviors this can be a soft sign to autism spectrum disorders. If increasing head size over time, can also be due to CSF fluid leaks causing that increase, hydrocephalus Neurologist need