pyramid

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A solid figure with a polygonal base and triangular faces that meet at a common point.
• noun Something shaped like this polyhedron.
• noun A massive monument of ancient Egypt having a rectangular base and four triangular faces culminating in a single apex, built over or around a crypt or tomb.
• noun Any of various similar constructions, especially a four-sided Mesoamerican temple having stepped sides and a flat top surmounted by chambers.
• noun The transactions involved in pyramiding stock.
• noun Anatomy A structure or part suggestive of a pyramid in shape.
• intransitive verb To place or build in the shape of a pyramid.
• intransitive verb To build (an argument or thesis, for example) progressively from a basic general premise.
• intransitive verb To speculate in (stock) by making a series of buying and selling transactions in which paper profits are used as margin for buying more stock.
• intransitive verb To assume the shape of a pyramid.
• intransitive verb To increase rapidly and on a widening base.
• intransitive verb To pyramid stocks.

from The Century Dictionary.

• In stock-dealings on margin, to speculate or continue to speculate on one's profits, that is, to use the profit made on one transaction as margin on a second and the profit on that (if any) as margin on a third, etc.
• noun One of the five large pieces in the dental apparatus of some echinoids.
• noun A game of pool begun by arranging in a triangle 15 balls, which the various players in turn endeavor to pocket with a single cue-ball. Customarily each ball pocketed counts 1, and the player continues as long as ho makes at each stroke and does not pocket the cue-ball.
• noun A variety of checkers in which the pieces are arranged in the form of a pyramid.
• noun A massive structure of polygonal, usually square plan, the sides of which slope, each usually in one plane, to a common apex.
• noun In geometry, a solid contained by a plane polygon as base and other planes meeting in a point.
• noun In crystallography, a form, in any system but the isometric, bounded by eight, twelve, sixteen, or twenty-four planes, and consisting of two four-, six-, eight-, or twelve-sided pyramids placed base to base.
• noun In zoology and anatomy, a pyramidal or conical part, structure, or organ; specifically, a mass of longitudinal fibers on each side of the anterior median fissure of the oblongata. See cut under Elasmobranchii.
• noun The pile of five or six triangular valves covering an opening on the oral surface of the body of a cystic crinoid. The structure is variously interpreted as ovarian or oro-anal.
• noun In medieval architecture, a pinnacle of quadrangular plan, most commonly acutely pyramidal in form; hence, any similar feature. Compare pyramidion.
• noun The American columbo, or Indian lettuce, Frasera Carolinensis.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb (Speculation) To enlarge one's holding or interest in a series of operations on a continued rise or decline by using the profits to buy or sell additional amounts on a margin, as where one buys on a 10% margin 100 shares of stock quoted at 100, holds it till it rises to 105, and then uses the paper profit to buy 50 shares more, etc. The series of operations constitutes a pyramid. A similar process of reinvesting gains or winnings (as of a gamble), but not involving operation on margin, is called a parlay.
• transitive verb (Speculation) To use, or to deal in, in a pyramiding transaction. See pyramid, v. i.
• noun A solid body standing on a triangular, square, or polygonal base, and terminating in a point at the top; especially, a structure or edifice of this shape.
• noun (Geom.) A solid figure contained by a plane rectilineal figure as base and several triangles which have a common vertex and whose bases are sides of the base.
• noun (Billiards), engraving The game of pool in which the balls are placed in the form of a triangle at spot.
• noun (Finance) a fraudulent investment scheme in which the manager promises high profits, but instead of investing the money in a genuine profit-making activity, uses the money from later investors to pay the profits to earlier investors; -- also called pyramid scheme or pyramid operation. This process inevitably collapses when insufficient new investors are available, leaving the later investors with total or near-total losses of their investments. The managers usually blame government regulations or interference for the collapse of the scheme, rather than admit fraud.
• noun (Geom.) the perpendicular distance from the vertex to the plane of the base.
• noun (Geom.) a straight line drawn from the vertex to the center of the base.
• noun (Geol.) See Earth pillars, under Earth.
• noun (Geom.) a pyramid whose axis is perpendicular to the base.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An ancient massive construction with a square or rectangular base and four triangular sides meeting in an apex, such as those built as tombs in Egypt or as bases for temples in Mesoamerica.
• noun A construction in the shape of a pyramid, usually with a square or rectangular base.
• noun geometry A solid with triangular lateral faces and a polygonal (often square or rectangular) base.
• noun A pyramid scheme.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a polyhedron having a polygonal base and triangular sides with a common vertex
• verb arrange or build up as if on the base of a pyramid
• noun (stock market) a series of transactions in which the speculator increases his holdings by using the rising market value of those holdings as margin for further purchases
• verb increase rapidly and progressively step by step on a broad base
• verb enlarge one's holdings on an exchange on a continued rise by using paper profits as margin to buy additional amounts
• verb use or deal in (as of stock or commercial transaction) in a pyramid deal
• noun a massive monument with a square base and four triangular sides; begun by Cheops around 2700 BC as royal tombs in ancient Egypt