LUMEN By N., Sam M.S. - 5 is the opening area of the inside of a cylinder, or the unit of luminous flux. LUMEN: "The inner-part or hollow area within a cylindrical shape is otherwise known as the lumen." Related Psychology Terms REFLECTANCE ARTERIOSCLEROTIC BRAIN DISORDER MICROTUBULC LOCKE, JOHN (1632-1704) VESTIBULAR RECEPTORS NEURON (Nerve Cell) Dissociative Identity Disorder TALBOT PMDD: Can It Be Cured? HALLUCINATION Cite this page: N., Sam M.S., "LUMEN," in PsychologyDictionary.org, April 7, 2013, https://psychologydictionary.org/lumen/ (accessed June 25, 2022).