Source : Webster's Revised Unabridged Dictionary (1913)

Megalocephalia \Meg`a*lo*ce*pha"li*a\, Megalocephaly
\Meg`a*lo*ceph"a*ly\, n. [NL. megalocephalia, fr. Gr. ? having a
   large head.] (Med.)
   The condition of having an abnormally large head. --
   {Meg`a*lo*ce*phal"ic}, a.

Source : WordNet®

megalocephaly
     n : an abnormally large head; differs from hydrocephalus because
         there is no increased intracranial pressure and the
         overgrowth is symmetrical [syn: {macrocephaly}, {megacephaly}]