Geometrically, this "great" polyhedron has a polygonal base & sides which come to a common vertex
... adjacent angles - 2 
nonstraight and nonzero angles that have a common side in the interior of the ... 
planar closed curve (the base) to a common vertex; commonly, a right circular 
cone; .... polyhedron - a closed surface formed by polygonal plane faces, 
connected at the... [DOC] [TLE] Polyhedra and Polytopes - Numericana [PAR] Polyhedra in certain families are named after one prominent polygon.