Megacephaly is a medical condition characterized by an abnormally large head and brain size. It is commonly referred to as macrocephaly or megalencephaly. Other related terms include hydrocephaly, which is an abnormal accumulation of cerebrospinal fluid within the brain, and craniosynostosis, which is the premature fusion of the skull bones. Encephalocele, a protrusion of the brain tissue through a gap in the skull, is also a possible synonym for megacephaly. However, it is important to note that these conditions may have different underlying causes and treatments. Consult a healthcare provider for proper diagnosis and management of any suspected neurological condition.