The Collaborative International Dictionary of English v.0.48:

Shrove \Shrove\,
   imp. of Shrive.
   [1913 Webster]

   Shrove Sunday, Quinguagesima Sunday.

   Shrove Tuesday, the Tuesday following Quinguagesima Sunday,
      and preceding the first day of Lent, or Ash Wednesday.

   Note: It was formerly customary in England, on this day, for
         the people to confess their sins to their parish
         priests, after which they dined on pancakes, or
         fritters, and the occasion became one of merriment. The
         bell rung on this day is popularly called Pancake Bell,
         and the day itself Pancake Tuesday. --P. Cyc.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Quinquagesima \Quin`qua*ges"i*ma\, a. [L., fr. quinquagesimus
   the fiftieth, akin to quinquaginta fifty, quinque five. See
   Five.]
   Fiftieth.
   [1913 Webster]

   Quinquagesima Sunday, the Sunday which is the fiftieth day
      before Easter, both days being included in the reckoning;
      -- called also Shrove Sunday.
      [1913 Webster]