Cataclysm

Cataclysm is a term for a large-scale and violent upheaval that causes widespread disruption or destruction. The word originates from the Greek kataklysmos, meaning a deluge or flood, from kata "down" and klyzein "to wash away" or "to break down." In common usage it denotes a sudden, transformative event that alters landscapes, ecosystems, or societies.

In geology and earth science, cataclysm describes an abrupt change in the physical environment, such as floods, earthquakes, landslides, volcanic eruptions, or meteor impacts, which may leave a lasting geological or climatic signature and potentially trigger mass extinctions. Historically, the term has also been used to describe rapid deformations of the Earth's surface or climate that do not fit gradual-change models.

In cultural contexts, cataclysm is often used metaphorically to describe societal collapse or world-altering events in fiction, history, or religious narratives. The concept has applications in planetary science and planetary defense, where researchers consider potential cataclysmic events that could affect life on a given planet. Related terms include catastrophe and apocalypse, which carry broader or more moral implications. Cataclysm remains a flexible descriptor for events characterized by their scale, speed, and capacity to reconfigure a system.