plural of pyramid of doom

plural of renal pyramid

(simile) Extremely ancient.

plural of population pyramid

plural of oblique pyramid

Synonym of old as the Pyramids

An illicit money-making investment scheme whereby early investors are paid primarily or wholly by later investors. Eventually all such schemes fail to the detriment of recent (later) investors.

plural of pyramid scheme

(geometry) A three-dimensional geometric figure with a square base and four triangular sides that connect at one point. An example is the Great Pyramid of Giza.

A three-dimensional figure with four triangular bases.