<p><strong>Noun:</strong></p><ul><li>a more or less orderly pile or heap: a precariously balanced stack of books; a neat stack of papers.</li><li>a large, usually conical, circular, or rectangular pile of hay, straw, or the like (often used in combination): There was a strawstack in the corner of the field that the children liked to climb.</li><li>Informal: a large quantity or number: We've got a stack of great ideas for new projects, so I'm feeling optimistic about work.</li><li>There are stacks of family fun to be had at our newly renovated amusement park.</li><li>Often stacks: a set of shelves for books or other materials ranged compactly one above the other, as in a library.</li><li>stacks, the area or part of a library in which the books and other holdings are stored or kept.</li><li>Computers: a data structure programmed to consist of elements added one at a time and only removable one at a time in order of recency.</li><li>a data set or list arranged in this way, so that the last item stored is the first item retrieved or removed.</li><li>memory dedicated to temporary storage of data arranged this way.</li><li>a number of chimneys or flues grouped together.</li><li>smokestack (def 1).</li><li>a vertical duct for conveying warm air from a leader to a register on an upper story of a building.</li><li>a vertical waste pipe or vent pipe serving a number of floors.</li><li>Slang: a large quantity of money, especially one thousand dollars: He spent two stacks on those jeans.</li><li>A high-quality computer may cost a stack, but it'll last you longer than a cheap one.</li><li>Radio: an antenna consisting of a number of components connected in a substantially vertical series.</li><li>Military: a conical, free-standing group of three rifles placed on their butts and hooked together near the top of the barrel with an attached swivel.</li><li>Also called air stack, Aviation: a group of airplanes circling over an airport awaiting their turns to land.</li><li>an English measure for coal and wood, equal to 108 cubic feet (3 cu. m).</li><li>Geology: a column of rock isolated from a shore by the action of waves.</li><li>Games: a given quantity of chips that can be bought at one time, as in poker or other gambling games.</li><li>the quantity of chips held by a player at a given point in a gambling game.</li></ul><p><strong>Verb (used with object):</strong></p><ul><li>to pile, arrange, or place in a more or less orderly heap: I spent all yesterday loading and stacking hay bales by hand.</li><li>She stacked her papers and put away her tools, then got ready to leave.</li><li>to cover or load with something in stacks or piles: We stacked the car with luggage and headed out on our road trip.</li><li>to arrange or select unfairly in order to force a desired result, especially to load (a jury, committee, etc.) with members having a biased viewpoint: The lawyer charged that the jury had been stacked against his client.</li><li>to keep (a number of incoming airplanes) flying nearly circular patterns at various altitudes over an airport where crowded runways, a low ceiling, or other temporary conditions prevent immediate landings.</li></ul><p><strong>Verb (used without object):</strong></p><ul><li>to be arranged in or form a stack: These chairs stack easily.</li></ul><p><strong>Verb Phrase:</strong></p><ul><li>Informal: to compare; measure up (often followed by against): How does the movie stack up against the novel?</li><li>Informal: to appear plausible or in keeping with the known facts: Your story just doesn't stack up.</li><li>Aviation: to control the flight patterns of (airplanes waiting to land at an airport) so that each circles at a designated altitude.</li></ul>