pyramid

pyramid is a Noun

Definition:

[1] 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] 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] The game of pool in which the balls are placed in the form of a triangle at spot. [Eng.] Altitude of a pyramid (Geom.), the perpendicular distance from the vertex to the plane of the base. -- Axis of a pyramid (Geom.), a straight line drawn from the vertex to the center of the base. -- Earth pyramid. (Geol.) See Earth pillars, under Earth. -- Right pyramid (Geom.) a pyramid whose axis is perpendicular to the base.