In Christianity, a moveable feast or movable feast is a holy day — a feast day or a fast day — whose date is not fixed to a particular day of the calendar year but moves in response to the date of Easter, the date of which varies according to a complex formula. Easter is considered by some to itself be a "moveable feast".
By extension, other religions' feasts are occasionally described by the same term. In addition many countries have secular holidays that are moveable, for instance to make holidays more consecutive; the term "moveable feast" is not used in this case however.
Further, by metaphoric extension but with the meaning of a party that was on the move, Ernest Hemingway used the term A Moveable Feast for the title of his memoirs of life in Paris in the 1920s. This usage has become a popular phrase in food contexts, with several catering companies adopting it as their name.
Although Mardi Gras (also known as Shrove Tuesday) moves around the calendar because it is celebrated 47 days before Easter, it is not technically a moveable feast, because it is not a holiday on any church calendar.