Wiktionary
n. any apple primarily used for making pies, crumbles or sauces
WordNet
n. an apple used primarily in cooking for pies and applesauce etc [ant: eating apple]
Wikipedia
A cooking apple is an apple that is used primarily for cooking rather than eating raw. Cooking apples are larger, and can be tarter than eating varieties. Some varieties have a firm flesh that does not break down much when cooked. The British grow a large range of apples specifically for cooking, but such varieties are used worldwide, although apples eaten raw are also used for cooking purposes. Many apples are dual-purpose.
Apples can be cooked down into sauce, apple butter or fruit preserves, baked in an oven and served with custard, and made into pies or apple crumble. In the UK apples are commonly boiled and mashed and served as apple sauce with roast pork. Bramley apple is by far the most popular cooking apple in the UK.
A baked apple is one that has been baked in an oven until it has become soft. The core is usually removed and often stuffed with other fruits, brown sugar, raisins, or cinnamon.
John Claudius Loudon wrote in 1842
Properties of a good apple — Apples for table are characterised by a firm pulp, elevated, poignant flavour, regular form, and beautiful colouring; those for kitchen use by the property of falling as it is technically termed, or forming in general a pulpy mass of equal consistency when baked or boiled, and by a large size. Some sorts of apples have the property of falling when green, as the Keswick, Carlisle, Hawthornden, and other codlins; and some only after being ripe, as the russet tribes. Those which have this property when green are particularly valuable for affording sauces to geese early in the season, and for succeeding the gooseberry in tarts.