pyramid

pyr·a·mid

noun \ˈpir-ə-ˌmid\

Definition of PYRAMID

1

: a polyhedron having for its base a polygon and for faces triangles with a common vertex

2

: an anatomical structure resembling a pyramid: as a : renal pyramid b : either of two large bundles of motor fibers from the cerebral cortex that reach the medulla oblongata and are continuous with the corticospinal tracts of the spinal cord c : a conical projection making up the central part of the inferior vermis of the cerebellum