Shrove·tide 
(shrōvtīd′)
(shrōvtīd′)n.
The three days, Shrove Sunday, Shrove Monday, and Shrove Tuesday, preceding Ash Wednesday.
[Middle English schroftide : schrof-, shriving (from schriven, to shrive; see SHRIVE) + tid, time; see TIDE1 (so called because in medieval times it was customary for Christians to confess and be shriven in the week before Lent).]