fissure /fish″ər/ [L, fissura, cleft] , 1. a cleft or groove on the surface of an organ, often marking its division into parts, such as the lobes of the lung. 2. a cracklike lesion of the skin, such as an anal fissure. 3. a lineal fault on a bony surface that occurs during the development of a part, such as a fissure in the enamel of a tooth. A fissure is usually deeper than a sulcus, but in the terminology of anatomy fissure and sulcus are often used interchangeably. Also called fissura. −fissured, adj.
