Chemiluminescent is a technical term used to describe a process that produces light via a chemical reaction, without involving heat or any other external light source. There are several other words that can be used as synonyms for chemiluminescent, such as bioluminescent, phosphorescent, and fluorescent. Bioluminescent refers to the natural light emission by some living organisms, such as fireflies, jellyfish and microorganisms. Phosphorescent describes materials that emit light after absorbing photons, and fluorescent describes the phenomenon where a material absorbs one wavelength of light and emits another, usually a longer wavelength. In the field of science, these synonyms are often used to describe different forms of light emission phenomena.