#May_Day__First_of_May__May_1  observed in the United States to celebrate the coming of spring; observed in Russia in honor of labor
  supertype:  particular_day__day  a day assigned to a particular purpose or observance; "Mother's Day"
  part of:  May  the month following April and preceding June
     part of:  Gregorian_calendar__New_Style  the solar calendar now in general use, introduced by Pope Gregory XIII in 1582 AD to correct an error in the Julian calendar by suppressing 10 days, making Oct 5 be called Oct 15, and providing that only centenary years divisible by 400 should be leap years; it was adopted by Great Britain and the American colonies in 1752
     part of:  springtime__spring  the season of growth; "the emerging buds were a sure sign of spring"; "he will hold office until the spring of next year"

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