Bible Dictionaries
Black Monday

Webster's Dictionary

(1):

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.

(2):

The first Monday after the holidays; - so called by English schoolboys.

Bibliography Information
Webster, Noah. Entry for 'Black Monday'. Noah Webster's American Dictionary. https://www.studylight.org/​dictionaries/​eng/​web/​b/black-monday.html. 1828.