pyramid: n. 1 a monumental structure, usu. of stone, with a square base and sloping sides meeting centrally at an apex, esp. an ancient Egyptian royal tomb. 2 a solid of this type with a base of three or more sides. 3 a pyramid-shaped thing or pile of things. 4 (in pl.) a game played on a billiard-table with (usu. 15) coloured balls and a cue-ball. øpyramid selling a system of selling goods in which agency rights are sold to an increasing number of distributors at successively lower levels. øøpyramidal adj. pyramidally adv. pyramidic adj. (also pyramidical). pyramidically adv. pyramidwise adj. [ME f. L pyramis f. Gk puramis -idos]