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.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.