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1. An orderly pile, especially one arranged in layers: a stack of newspapers. See Synonyms at heap.
2. A large, usually conical pile of straw or fodder arranged for outdoor storage.
3. Computers A section of memory and its associated registers used for temporary storage of information in which the item most recently stored is the first to be retrieved.
4. A group of three rifles supporting each other, butt downward and forming a cone.
a. A chimney or flue.
b. A group of chimneys arranged together.
6. A vertical exhaust pipe, as on a ship or locomotive.
a. An extensive arrangement of bookshelves.
b. The area of a library in which most of the books are shelved.
8. A stackup.
9. An English measure of coal or cut wood, equal to 108 cubic feet (3.06 cubic meters).
10. Informal A large quantity: a stack of work to do.
v. stacked, stack·ing, stacks
1. To arrange in a stack; pile.
2. To load or cover with stacks or piles: stacked the dishwasher.
a. Games To prearrange the order of (a deck of cards) so as to increase the chance of winning.
b. To prearrange or fix unfairly so as to favor a particular outcome: tried to stack the jury.
4. To direct (aircraft) to circle at different altitudes while waiting to land.
To form a stack: Make sure the boxes stack neatly against the wall.
stack up Informal
1. To measure up or equal: Their gift doesn't stack up against his.
2. To make sense; add up: Her report just doesn't stack up.
[Middle English stak, pile, heap, haystack, from Old Norse stakkr.]
(Aeronautics) the arrangement of aircraft traffic in busy flight lanes, esp while waiting to land at an airport, with a minimum vertical separation for safety of 1000 feet below 29 000 feet and 2000 feet above 29 000 feet