pestis

Pestis is a Latin noun that translates as "pest" or "plague." In ancient and medieval Latin, pestis referred to calamities perceived as highly contagious, deadly, or widespread harm, and later came to denote outbreaks of infectious disease.

In historical texts, pestis is commonly used to describe plague outbreaks. The most famous association is with the Black Death of the 14th century, but Latin chronicles and medical writers used pestis for various epidemic diseases.

In modern science, pestis survives mainly as part of the binomial name of the plague bacterium, Yersinia pestis, the agent of plague. Plague can present as bubonic, septicemic, or pneumonic forms and has caused several major pandemics in history; today it is treatable with antibiotics and preventable with public health measures, though it remains endemic in parts of the world.

Linguistically, pestis appears in related terms such as pestilent and pestilence, and in many languages as a root meaning "plague" or "pest." In taxonomy, pestis is used as a species epithet to indicate association with plague, notably in Yersinia pestis.