Fis″sure (?), n. [L. fissura, fr. findere, fissum, to cleave, split; akin to E. bite: cf. F. fissure.] A narrow opening, made by the parting of any substance; a cleft; as, the fissure of a rock.
Cerebral fissures(Anat.), the furrows or clefts by which the surface of the cerebrum is divided; esp., the furrows first formed by the infolding of the whole wall of the cerebrum. — Fissure needle(Surg.), a spiral needle for catching together the gaping lips of wounds. Knight. — Fissure of rolando(Anat.), the furrow separating the frontal from the parietal lobe in the cerebrum. — Fissure of Sylvius(Anat.), a deep cerebral fissure separating the frontal from the temporal lobe. See Illust. under Brain. — Fissure vein(Mining), a crack in the earth's surface filled with mineral matter. Raymond.