The word is a modern scientific compound, meticulously constructed from classical roots to describe a precise physical phenomenon. The first element, 'thermo-', originates from the Greek 'thermos' (hot), a descendant of the Proto-Indo-European root gwher- (to heat, warm). The second element, 'luminescence', is built on the Latin 'lumen' (light), from the PIE root leuk- (light, brightness), combined with the Latin-derived suffix '-escence' indicating a process or state. Thus, the term's literal construction, "heat-light-emission process," logically captures the essence of the event: light emission triggered specifically by the application of heat, as opposed to other forms of excitation like electricity or chemical reaction.

Structure: thermo (heat) + luminescence (light emission) thermo: From Greek 'thermos', meaning hot or heat. A combining form used in scientific terms. luminescence: From Latin 'lumen', meaning light, plus the suffix '-escence' denoting a state or process of being. It refers to the emission of light not resulting from heat.