1.
[Religion]the Tuesday in February that is the last day before the Christian season of lent, mainly used in Amercian English, the British word is Shrove Tuesday
2.
in some countries, a celebration with parties and marches in the streets that often lasts for several days and ends on the night before Lent begins
3.
a celebration with parties and marches in the streets at any time of the year, mainly used in Australian English