The famous “Black Death” that struck Europe during the 14th century is thought to have been an outbreak of:

The famous "Black Death" that struck Europe during the 14th century is thought to have been an outbreak of the Bubonic Plague.

Here are the steps to answer this question:

1. Understand the question: The question is asking about the disease that caused the "Black Death" in Europe during the 14th century.

2. Research: The "Black Death" was one of the most devastating pandemics in human history, resulting in the deaths of an estimated 75-200 million people in Eurasia, peaking in Europe from 1347 to 1351.

3. Answer: Based on historical records and scientific analysis from remains of victims, it is widely believed that the "Black Death" was an outbreak of the Bubonic Plague. This disease is caused by the bacterium Yersinia pestis, which humans can get after being bitten by a flea that has bitten an infected rodent, such as a rat.

4. Explanation: The Bubonic Plague is characterized by swollen lymph nodes, or "buboes," along with fever, chills, and weakness. It is called the "Black Death" because of the gangrene that can result, turning body parts black.