prismatoid vs polyhedron

prismatoid and polyhedron both are nouns.

Word	Noun	Adjective	Verb	Adverb
prismatoid	Yes	No	No	No
polyhedron	Yes	No	No	No

As nouns, polyhedron is a hypernym of prismatoid; that is, polyhedron is a word with a broader meaning than prismatoid:

prismatoid: a polyhedron whose vertices all lie in one or the other of two parallel planes; the faces that lie in those planes are the bases of the prismatoid
polyhedron: a solid figure bounded by plane polygons or faces

prismatoid (noun)	polyhedron (noun)
a polyhedron whose vertices all lie in one or the other of two parallel planes; the faces that lie in those planes are the bases of the prismatoid	a solid figure bounded by plane polygons or faces