fissure

(fĭshˈər)

1. A long narrow opening; a crack or cleft.
2. The process of splitting or separating; division.
3. A separation into subgroups or factions; a schism.
4. Anatomy A normal groove or furrow, as in the liver or brain, that divides an organ into lobes or parts.
5. Medicine A break in the skin, usually where it joins a mucous membrane, producing a cracklike sore or ulcer.