It appears in many words related to fire, heat, or light, such as:
* Pyre: A funeral pyre, a pile of wood for burning a dead body.
* Pyromania: An uncontrollable impulse to set things on fire.
* Pyrotechnics: The art of making fireworks.
* Pyrolysis: The decomposition of a substance by heat.
Note: The word "pyr" is sometimes used in its own right as a short form of "pyre" or "pyrotechnics".