BLACK FRIDAY n.
Any Friday on which a public disaster has occurred, as: In England, December 6, 1745, when the news of the landing of the Pretender reached London, or May 11, 1866, when a financial panic commenced. In the United States, September 24, 1869, and September 18, 1873, on which financial panics began.
BLACK MONDAY n. 2 definitions
Easter Monday, so called from the severity of that day in 1360, which was so unusual that many of Edward III.'s soldiers, then before Paris, died from the cold. Stow. Then it was not for nothing that may nose fell a bleeding on Black Monday last. Shak.