Carnival's wild excess was partly about emptying the pantry before Lent
Pancakes, doughnuts and feasting on Shrove Tuesday had a practical side: butter, milk and other animal products were used up so nothing spoiled during the Lenten fast. Wrapped around that thrift is something older, a festival of masks and upside-down rules that echoes Roman Saturnalia and rites for chasing winter away.
Carnival, also called Shrovetide in some places, is the festive run-up to Lent, covering Shrove Sunday, Shrove Monday and Shrove Tuesday, also known as Mardi Gras. Parades, street parties, costumes and masks let people shed their everyday identities for a shared sense of belonging, and indulgence is the point before a season of restraint, when Christians give something up and traditionally donate the money saved as alms.
It also has a quieter religious side. Lutherans, Anglicans and Catholics use Shrove Tuesday for self-examination and repentance. Many churches collect the previous year's Palm Sunday branches in a basket and burn them on Shrove Tuesday, producing the ashes used the next morning on Ash Wednesday. Other customs include Shrovetide rods and buns eaten after church.
Names track denominations. Catholic regions and Greece say Carnival, historically Lutheran countries say Fastelavn, Anglican and Methodist areas say Shrovetide, and Slavic Orthodox countries hold Maslenitsa in the final week before Great Lent. Across the Dutch and German-speaking lands the season traditionally opens on the eleventh of November, often at 11:11 in the morning, a date tied to St. Martin's Day festivities.
The word's origin is argued over. The usual derivation is Late Latin carne levare, to remove meat, with carne vale, farewell to meat, as a popular folk version that some revellers happily read as farewell to the flesh. Other scholars point to a rustic feast called carnualia, or to the Navigium Isidis, when a decorated boat, the carrus navalis, led masked marchers to the sea to bless the sailing season, possibly inspiring both the name and parade floats. Anthropologists see a reversal ritual descended from the Greek Anthesteria and Roman Saturnalia, where hierarchy was briefly overturned so order could return renewed, and a rite of passage from winter's darkness into spring.
Source: Carnival