Fissure
FIS'SURE, noun fish'ure. [Latin fissura, from findo, to split.]
1. A cleft; a narrow chasm made by the parting of any substance; a longitudinal opening; as the fissure of a rock.
2. In surgery, a crack or slit in a bone, either transversely or longitudinally, by means of external force.
3. In anatomy, a deep, narrow sulcus, or depression, dividing the anterior and middle lobes of the cerebrum on each side.
FIS'SURE, verb transitive To cleave; to divide; to crack or fracture.