Source of illumination is a term used to describe any device or object that produces LIGHT. The three crossword solutions for this term are 'LAMP' (4 letters), 'LIGHT' (5 letters), and 'Ultraviolet LAMP' (15 letters). A LAMP is a device that produces LIGHT, usually through the use of electricity or a fuel source. LIGHT is a form of energy that is visible to the human eye. Ultraviolet lamps are special lamps that produce ultraviolet radiation, which is a type of LIGHT that is invisible to the human eye.