From black (“bad; ill-omened; marked by disaster”). Friday is an ill-omened day according to ancient superstition, so a Friday that was darkened by another ill-omen (such as being the 13th) or an actual disaster became known as "Black Friday". Philadelphia police applied the term to the day after Thanksgiving because the large number of people out shopping made traffic chaotic; it was later re-analysed as denoting that it was the first day of the year on which retailers typically posted profits ('in the black') rather than losses ('in the red').
- A Friday falling on the 13th day of the month (and therefore doubly ill-omened).
- Any Friday actually darkened by catastrophe, or the anniversary thereof.
- (possibly obsolete) Good Friday.
- (US, Canada, business, retailing) The day after US Thanksgiving Day, generally regarded as the first day of the Christmas season, and the busiest shopping day of the year. Observed in the US and, more recently, Canada.
- (by extension) The sales period involving heavy price reductions immediately following US Thanksgiving Day, from Friday (the original Black Friday) through Monday (Cyber Monday).