brachycephalic /ˌbɹæk.ɪ.səˈfæl.ɪk/adjective 1noun 1forms 2 adjective1 •Having a head that is short from front to back (relative to its width from left to right); having a broad skull with a cephalic index over 80."Round-headed," he muttered. "Brachycephalic, gray-eyed, black-haired, with suggestion of the negroid. Celtic, I presume?" — 1912 noun1 •A brachycephalic person or creature; someone with a short, broad skull, typically indicated by a cephalic index over 80. formsbrachycephali · brachycephalics