septum pellucidum
noun
septum pel·lu·ci·dum
| \ -pə-ˈlü-sə-dəm
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plural septa pellucida\ -də
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Medical Definition of septum pellucidum
: the thin double partition extending vertically from the lower surface of the corpus callosum to the fornix and neighboring parts, separating the lateral ventricles of the brain, and enclosing the fifth ventricle