The word itself, "Halloween," actually has its origins in the Catholic Church. It comes from a contracted corruption of All Hallows Eve. November 1, "All Hollows Day" (or "All Saints Day"), is a Catholic day of observance in honor of saints. But, in the 5th century BC, in Celtic Ireland, summer officially ended on October 31. The holiday was called Samhain (pronounced sow-in), which means "end of summer", the Celtic New year.