pachycephalic
/ˌpakɪsɪˈfalɪk/ /ˌpakɪkɪˈfalɪk/originally Physical Anthropol. Now rare
adjective
Having a very thick skull; exhibiting pachycephaly. Later also (humorous ): thickheaded, stupid.
Origin
Late 19th century; earliest use found in Journal of the Royal Anthropological Institute. From pachy- + -cephalic, after scientific Latin Pachycephali thick heads.