Mardi Gras

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Shrove Tuesday, celebrated as a holiday in many places with carnivals, masquerade balls, and parades of costumed merrymakers.
• noun A carnival period coming to a climax on this day.
• noun An occasion of great festivity and merrymaking.

from The Century Dictionary.

• noun Shrove Tuesday; the last day of carnival; the day before Ash Wednesday (the first day of Lent), which in some places, as in New Orleans, is celebrated with revelry and elaborate display.

from the GNU version of the Collaborative International Dictionary of English.

• noun The last day of Carnival; the Tuesday before Ash Wednesday (the beginning of Lent and fasting); Shrove Tuesday; -- in some cities a great day of carnival and merrymaking; in the United States it is especially associated with New Orleans.
• noun The series of festival events celebrated on Mardi Gras{1}.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The day, also known as Shrove Tuesday, when traditionally all fat and meat in the house were finished up, before Christians were banned from eating them during Lent, which commenced the following day on Ash Wednesday.
• noun The last day of a carnival, traditionally the celebration immediately before the start of Lent when joy would be out of place for Christians.
• noun A carnival.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a carnival held in some countries on Shrove Tuesday (the last day before Lent) but especially in New Orleans
• noun the last day before Lent