Source : Webster's Revised Unabridged Dictionary (1913)

Megacephalic \Meg`a*ce*phal"ic\, Megacephalous
\Meg`a*ceph"a*lous\, a. [Mega- + Gr. kefalh` head.] (Biol.)
   Large headed; -- applied to animals, and to plants when they
   have large flower heads.