pyramid

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A solid figure with a polygonal base and triangular faces that meet at a common point.
2. n. Something shaped like this polyhedron.
3. n. 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.
4. n. Any of various similar constructions, especially a four-sided Mesoamerican temple having stepped sides and a flat top surmounted by chambers.
5. n. The transactions involved in pyramiding stock.
6. n. Anatomy A structure or part suggestive of a pyramid in shape.
7. v. To place or build in the shape of a pyramid.
8. v. To build (an argument or thesis, for example) progressively from a basic general premise.
9. v. 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.
10. v. To assume the shape of a pyramid.
11. v. To increase rapidly and on a widening base.
12. v. To pyramid stocks.

Century Dictionary and Cyclopedia

1. n. A massive structure of polygonal, usually square plan, the sides of which slope, each usually in one plane, to a common apex. Pyramids have been erected in different parts of the world, especially in Egypt, where there are numerous groups in different styles of execution and states of preservation. By far the most interesting of these groups is that of Ghizeh, near Cairo, where there are three pyramids of large size, and several smaller ones. All the Egyptian pyramids were built for tombs, and certainly in most cases, if not in all, for royal personages. They are remarkable not only for the great size of many of them, but for the manner in which they were hermetically sealed, there being no external opening of any kind, nor any indication of the place in which the mummy had been deposited; on the contrary, some of them exhibit very ingenious arrangements intended to lead astray those searching for the sepulchral chamber. Everything was planned in their construction to insure permanence, concealment, and security from violation. Of the three great pyramids at Ghizeh, the largest and by far the most important and interesting is the so-called Great Pyramid, in regard to which a very extensive literature exists, and which has frequently been measured and elaborately described. It is the largest work of man's hands in the world, having been originally 481 feet in height, and each of the sides of its very nearly square base measuring on the average nearly 756 feet (9068.8 in., Petrie). It is the only one remaining of the “seven wonders of the world.” Its interior structure is more elaborate than that of any of the other pyramids, and some of the features which it displays are peculiar, and remarkable as showing the desire of the builders that at least one geometrical fact of fundamental importance should be incorporated into the structure. Thus the height of the Great Pyramid bears, with remarkable precision, the same relation to the total length of the four sides of its base that the radius of a circle has to its circumference, and other indications of the π ratio exist in its interior. This and other interesting peculiarities of this pyramid have led various persons, some of whom have been eminent in science, to adopt the view that it was a divinely inspired building, and that the so-called “coffer” contained within the principal sepulchral chamber was intended to serve as a standard of weights and measures and a record of various fundamental facts in geophysics, and not for a sarcophagus. Of the manner in which the huge stones of which this pyramid is built were raised to their present position but little is definitely known, but it is inferred that the work was done without the aid of complicated machinery; that they were shaped — to a very considerable extent at least — by the use of saws of bronze, the teeth of which were gems or hard stones, has been clearly shown by the most recent investigations. The date of the Great Pyramid, which is believed to have been built by or for King Shufu (Cheops) of the fourth dynasty, is variously fixed by Egyptologists at from 2450 to 4235 (b. c.) The latter is the date assigned by Mariette.
2. n. In geometry, a solid contained by a plane polygon as base and other planes meeting in a point. This point is called the vertex of the pyramid; and the planes which meet in the vertex are called the sides, which are necessarily all triangles, having for their bases the sides of the base of the pyramid. Any pyramid is in volume one third of a prism that has the same base and altitude. Pyramids are denominated from the figures of their bases, being triangular, square, pentagonal, etc., according as the base is a triangle, a square, a pentagon, etc.
3. n. 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. The name is also extended to embrace any form the planes of which intersect all three of the axes; in the monoclinic system it includes only four, and in the triclinic only two planes, being in each case an open form. If the plants intersect the lateral axes at the assumed unit distances, the pyramid is called a unit pyramid; other forms are designated macropyramids, clinopyramids, etc. (see these terms), according to their position. In the tetragonal system a unit pyramid is also called a protopyramid, or pyramid of the first order or series, and a square octahedron formed by pyramidal planes parallel to one of the lateral axes is in distinction called a deuteropyramid or diametral pyramid, or one of the second order or series. These terms are also used in an analogous manner in the hexagonal system.
4. n. 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.
5. n. 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.
6. n. In medieval architecture, a pinnacle of quadrangular plan, most commonly acutely pyramidal in form; hence, any similar feature. Compare pyramidion.
7. n. The American columbo, or Indian lettuce, Frasera Carolinensis.
8. n. One of the five large pieces in the dental apparatus of some echinoids.
9. n. 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.
10. n. A variety of checkers in which the pieces are arranged in the form of pyramid.
11. 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.

Wiktionary

1. n. 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.
2. n. A construction in the shape of a pyramid, usually with a square or rectangular base.
3. n. geometry A solid with triangular lateral faces and a polygonal (often square or rectangular) base.
4. n. A pyramid scheme.

GNU Webster's 1913

1. n. 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.
2. n. (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.
3. n. (Billiards), engraving The game of pool in which the balls are placed in the form of triangle at spot.
4. n. (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.
5. v. (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.
6. v. (Speculation) To use, or to deal in, in a pyramiding transaction. See pyramid, v. i.

WordNet 3.0

1. n. a polyhedron having a polygonal base and triangular sides with a common vertex
2. v. arrange or build up as if on the base of a pyramid
3. n. (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
4. v. increase rapidly and progressively step by step on a broad base
5. v. enlarge one's holdings on an exchange on a continued rise by using paper profits as margin to buy additional amounts
6. v. use or deal in (as of stock or commercial transaction) in a pyramid deal
7. n. a massive monument with a square base and four triangular sides; begun by Cheops around 2700 BC as royal tombs in ancient Egypt