Pyramid

a massive monument with a square base and four triangular sides; begun by Cheops around 2700 BC as royal tombs in ancient Egypt

a polyhedron having a polygonal base and triangular sides with a common vertex

(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

arrange or build up as if on the base of a pyramid

enlarge one's holdings on an exchange on a continued rise by using paper profits as margin to buy additional amounts

increase rapidly and progressively step by step on a broad base

use or deal in (as of stock or commercial transaction) in a pyramid deal