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