Definitions for habenula
A circumscript mass of cells in the caudal and dorsal aspect of the dorsal thalamus
Origin: From Latin habenula, diminutive of habena.
U.S. National Library of Medicine
A small protuberance at the dorsal, posterior corner of the wall of the third ventricle, adjacent to the dorsal thalamus and pineal body. It contains the habenular nuclei and is a major part of the epithalamus. (From Lockard, Desk Reference for Neuroscience, 2nd ed, p121)