Also English Black Death, Black Plague, Latin Atra mors, German schwarzer Tod, Icelandic svarti dauði, French la mort noire for the pandemic outbreak of bubonic plague throughout Europe and most of Asia in the 14th century that killed nearly half the population of Europe and Asia.

The 1347 pandemic plague was not referred to specifically as "black," at the time, in any European language. The expression "black death" had occasionally been applied to other fatal or dangerous diseases. In English, "Black death" was not used to describe this plague pandemic, however, until the 1750s; the term is first attested in 1755, where it translated Danish: den sorte død, lit. 'the black death'.

This expression — as a proper name for the pandemic — had been popularized by Swedish and Danish chroniclers in the 15th and early 16th centuries, and in the 16th and 17th centuries, it was transferred to other languages as a calque. Previously, most European languages had named the pandemic a variant or calque of the Latin magna mortalitas, lit. 'Great Death'.

The phrase 'black death' – describing Death as black – is very old. Homer used it in the Odyssey to describe the monstrous Scylla, with her mouths "full of black Death" (πλεῖοι μέλανος Θανάτοιο). Seneca the Younger may have been the first to describe an epidemic as 'black death', (mors atra) but only in reference to the acute lethality and dark prognosis of disease. The 12th–13th century French physician Gilles de Corbeil had already used atra mors to refer to a "pestilential fever" (febris pestilentialis) in his work On the Signs and Symptoms of Diseases (De signis et symptomatibus aegritudium). The phrase mors nigra, 'black death', was used in 1350 by Simon de Covino (or Couvin), a Belgian astronomer, in his poem "On the Judgement of the Sun at a Feast of Saturn" (De judicio Solis in convivio Saturni), which attributes the plague to an astrological conjunction of Jupiter and Saturn. His use of the phrase is not connected unambiguously with the plague pandemic of 1347 and appears to refer to the fatal outcome of disease.

The historian Elizabeth Penrose, writing under the pen-name "Mrs Markham", described the 14th-century outbreak as the "black death" in 1823. The historian Cardinal Francis Aidan Gasquet wrote about the Great Pestilence in 1893 and suggested that it had been "some form of the ordinary Eastern or bubonic plague". In 1908, Gasquet said use of the name atra mors for the 14th-century epidemic first appeared in a 1631 book on Danish history by J. I. Pontanus: "Commonly and from its effects, they called it the black death" (Vulgo & ab effectu atram mortem vocitabant).

Oxford English Dictionary Online https://www.oed.com/view/Entry/280254 

d'Irsay S (1926). "Notes to the Origin of the Expression: ≪ Atra Mors ≫". Isis. 8 (2): 328–32. doi:10.1086/358397. ISSN 0021-1753. JSTOR 223649

Horrox R (1994). The Black Death. Manchester: Manchester University Press.

Hecker, J. F. C. (1832). Der schwarze Tod im vierzehnten Jahrhundert. Berlin.

Gasquet FA (1893). The Great Pestilence AD 1348 to 1349: Now Commonly Known As the Black Death. https://www.gutenberg.org/ebooks/45815