A pie is a baked dish which is usually made of a pastry dough shell that covers or completely contains a filling of various sweet or savoury ingredients. Pies can be either "filled", where a dish is covered by pastry and the filling is placed on top of that, "top-crust," where the filling is placed in a dish and covered with a pastry/potato mash top before baking, or "two-crust," with the filling completely enclosed in the pastry shell. Pies can be a variety of sizes, ranging from bite-size to ones designed for multiple servings.
Reference to "pyes" as food items appeared in England (in a Latin context) as early as the 12th Century, but no unequivocal reference to the item with which the article is concerned is attested in the Oxford English Dictionary until the 14th century (Oxford English Dictionary sb pie).