Macrocephaly

n. excessive largeness of the head, megalocephaly

Macrocephaly (from the Greek words μακρύς, meaning "long", and κεφάλη, meaning "head"), is when the head circumference is larger than average for the age and sex of the infant or child. It is sometimes associated with certain disorders. Macrocephaly also may be inherited. Macrocephaly may be caused by an enlarged brain or hydrocephalus. It may be associated with other disorders such as dwarfism, autism, neurofibromatosis, glutaric acidemia type 1 (GA1), tuberous sclerosis and Cowden disease (multiple hamartoma syndrome).
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Macrocephaly /mac·ro·ceph·a·ly/ megalocephaly ; unusually large size of the head.macrocephal´ic mac·ro·ceph·a·ly or mac·ro·ce·pha·li·a n. [more]Macrocephaly - Community and Resources

Noun
1. an abnormally large head; differs from hydrocephalus because there is no increased intracranial pressure and the overgrowth is symmetrical
(synonym) megacephaly, megalocephaly
(hypernym) abnormality, abnormalcy, abnormal condition

An abnormally large head.