Entry 1 sense Webster, 1913 Mesocephalic · Mes·o·ce·phal·ic · IPA 01 a. Of or pertaining to, or in the region of, the middle of the head; as, the mesocephalic flexure. 1. Of or pertaining to, or in the region of, the middle of the head; as, the mesocephalic flexure.(Anat.)