The Collaborative International Dictionary of English v.0.48:

Brachycephalic \Brach`y*ce*phal"ic\, Brachycephalous
\Brach`y*ceph"a*lous\, a. [Gr. brachy`s short + ? head.] (Anat.)
   Having the skull short in proportion to its breadth;
   shortheaded; -- in distinction from dolichocephalic.
   [1913 Webster] Brachycephaly

WordNet (r) 3.0 (2006):

brachycephalic
    adj 1: having a short broad head with a cephalic index of over
           80 [syn: brachycephalic, brachycranial,
           brachycranic] [ant: dolichocephalic,
           dolichocranial, dolichocranic]
    n 1: an adult with a short broad head