Black Death, an epidemic of bubonic plague that appeared in Europe in the 1300's. The origin of the name is uncertain; it may come from a mistranslation of the Latin atra mors ("terrible death"). The Black Death was the most dreadful plague in the history of Europe. Historians estimate that in three years the plague killed at least one-third of Europe's population. Its severity was due in part to the people's low resistance to disease; most suffered from years of malnutrition.

The plague had three main forms. One affected the lungs and led to spitting of blood. Another was marked by large carbuncles on the neck, armpits, and groin. The third form fatally infected the blood. Nearly all stricken persons died within three days, many within 12 hours. Rats and fleas carried the disease; the fleas transmitted it to humans. The plague was also transmitted by persons who carried the disease in their lungs.

The Black Death probably began in Turkistan before spreading to Europe and Africa. In 1346, the pestilence appeared at a Black Sea port in the Crimea. The next year traders brought it to Sicily, from where it spread throughout the Italian peninsula. The plague struck France and the British Isles in 1348. By the end of 1350, it had spread to Germany, Scandinavia, and most of the other countries of Europe.

The epidemic led to terror and hysteria among the masses. Jews were accused of poisoning wells, and many were massacred. Some of the people joined a new religious cult, the Flagellants. They believed the plague to be God's punishment for people's sins, and flogged themselves to win God's mercy.

The plague reappeared in less violent form three times before the end of the century. Between 1400 and about 1700 it returned many times.

The Black Death hastened the breakup of medieval society. Agriculture came to a near standstill. Production fell, goods became scarce, and prices rose. Many peasants and workers died, laborers became scarce, and wages rose. During the confusion many serfs left the manors to which they were attached. Laws were adopted to freeze wages and prices. Governments tried to force serfs to return to their old manorial bondage. Peasant revolts broke out in England, France, and elsewhere.