1) The day before Shrove Tuesday, on which the customary dish was collops, that is rashers of bacon or other meat.
1613 March 6 Warrener’s account ... this Collop Monday of all the connyes kylled, Brandsby
1627 On Collop munday 1s and 2s to William Ellrington’s sister, Elmswell
1797 27 Feb. Collop Monday. I met Roger Pinkney on Elmire Moor, Sessay.