noun: Advent, the period from Advent Sunday (inclusive) through the start of Epiphany.
noun: Christmastide, Yuletide; the Twelve Days of Christmas, starting on Christmas Day and ending on Epiphany, January 6.
noun: (US, informal, retail and marketing) The winter season starting around Thanksgiving (typically Black Friday) and ending at or about New Year's Eve.
noun: (informal, business, marketing) The period at the end of the year when retailers promote Christmas shopping opportunities
