MICROCEPHALOUS

microcephalic, microcephalous, nanocephalic

(adjective) having an abnormally small head and underdeveloped brain; “a nanocephalic dwarf”

Source: WordNet® 3.1

Etymology

Adjective

microcephalous (comparative more microcephalous, superlative most microcephalous)

microcephalic

Source: Wiktionary

Mi`cro*ce*phal"ic, Mi`cro*ceph"a*lous, a. Etym: [Micro- + cephalic, cephalous.] (Anat.)

Definition: Having a small head; having the cranial cavity small; -- opposed to Ant: megacephalic.

Source: Webster’s Unabridged Dictionary 1913 Edition