Which term describes the process of emitting light due to heat?

The term that describes the process of emitting light due to heat is "incandescent." This phenomenon occurs when a material is heated to a temperature that causes it to emit visible light. Common examples include traditional incandescent light bulbs, where a metal filament is heated until it glows bright enough to produce light.

In contrast, fluorescent light works on a different principle, relying on the excitation of gas molecules to produce light, while LED technology utilizes semiconductor materials to emit light through electroluminescence. Bioluminescent refers to a natural process where living organisms produce light through chemical reactions, such as in fireflies or certain types of jellyfish. Each of these terms represents distinct mechanisms for light emission, highlighting why "incandescent" is the correct choice in this context.