Parasagittal section. Home » Parasagittal section. Definition. noun. (anatomy) A cut (in actual or by imaging techniques) parallel to the sagittal section. Supplement. Parasagittal section is also used synonymously with sagittal section to describe a vertical cut (or division), thus, producing right and left portions. However, sagittal section is often used to refer to the section along the midline. Thus, any section parallel to it is called parasagittal section.