<p><strong>Noun</strong></p><ul><li>Lumen</li><li>Lumens</li><li>Lumina</li></ul><p><strong>Definitions</strong></p><ul><li>Optics: The unit of luminous flux, equal to the luminous flux emitted in a unit solid angle by a point source of one candle intensity.</li><li>Anatomy: The canal, duct, or cavity of a tubular organ.</li><li>Botany: (of a cell) The cavity that the cell walls enclose.</li></ul><p><strong>End of Response</strong></p>