(anatomy) A major collection of axons that transmits nerve impulses from the motor cortex to the spinal cord.

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

plural of square pyramid

(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.

plural of triangular pyramid

A pyramid composed of several stacked platforms or mastabas so that each face has steps.

plural of stepped pyramid

Alternative form of step pyramid