Emily Dickinson Lexicon

SAG'IT-TAL, a. [L. sagittalis, from sagitta, an arrow; that which is thrown or driven, probably from the root of say and sing.]

Pertaining to an arrow; resembling an arrow; as, sagittal bars of yellow. – Pennant. In anatomy, the sagittal suture is the suture which unites the parietal bones of the skull. – Coxe.