Per Merriam (Webster that is)...
Mardi Gras MAR-dee-grah noun
1 a : Shrove Tuesday often observed (as in New Orleans) with parades and festivities *b : a carnival period climaxing on Shrove Tuesday
2 : a festive occasion resembling a pre-Lenten Mardi Gras
Did you know? "Mardi Gras," which literally means "fat Tuesday" in French, is the term for Shrove Tuesday, the Tuesday before Ash Wednesday and the Christian period of Lent. Though Mardi Gras has been celebrated since at least the Middle Ages in Europe, the celebration did not arrive in America until 1699, when, according to tradition, a group of French explorers held a Mardi Gras celebration downstream from the site of what is now New Orleans. In modern times the festive revelry and extravagant parades and costumes that are hallmarks of the carnival tradition are alive and well in both France and New Orleans, as well as other places around the globe.
*Indicates the sense illustrated in the example sentence.
For more info on Shrove Tuesday .