black monday

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. Stow. [ 1913 Webster ]

Then it was not for nothing that my nose fell a bleeding on Black Monday last. Shak. [ 1913 Webster ]

2. The first Monday after the holidays; -- so called by English schoolboys. Halliwell. [ 1913 Webster ]