Which Czech holiday is the equivalent of the French "Mardi Gras"?

Mardi Gras and Masopust are both Carnival celebrations. They both culminate on the day before Ash Wednesday, closing the pre-Lenten season. Lent, in the Christian church, is a period of penitential preparation for Easter. So, the pre-Lenten carnivals like Mardi Gras or Masopust, include the practice of the last night of eating rich, fatty foods before the ritual Lenten sacrifices and fasting of the Lenten season.

Mardi Gras is a French expression for "Fat Tuesday". In Czech, the word masopust (like its English counterpart "carnival") means "good-bye to meat". In the center of the celebrations, stand the mask, dance and the procession.

Štědrý den is the 24th of December. Its Czech name literally means "Generous Day", probably for the wealth of food that has traditionally been served for Christmas dinner.

"Silvestr" is the Czech name for New Year's Eve.

St.Martin's Day is celebrated on November 11, it's a holiday of good food and drink. Fattened geese is a standard food for this celebration.