Definition of Black Friday in English:

Black Friday

noun

  • The day after Thanksgiving, regarded as the first day of the traditional Christmas shopping season, on which retailers offer special reduced prices.

    ‘shoppers were snapping up deals on Black Friday’

Origin

Early 17th century (as school slang, in the sense ‘Friday on which an examination is held’). The shopping sense dates from the 1960s and was originally used with reference to congestion created by shoppers; it was later explained as a day when retailers’ accounts went from being “in the red” to “in the black”.