Luminous radiation, also known as visible light, is a form of energy that is emitted from a source and is visible to the human eye. The term 'luminous radiation' can be broken down into two parts: luminous, which means emitting or reflecting light, and radiation, which is the emission of energy in the form of waves or particles. The crossword solution for this term is AURA, which is a luminous glow or halo around a person or object.