Definition of prismatoid in US English:

prismatoid

adjective

  • Chiefly Geometry. Relating to a prismatoid; prismoidal.

noun

  • Geometry. A generalized polyhedron all of whose vertices lie in one or other of two parallel planes.

Origin

Mid 19th century (in an earlier sense). From ancient Greek πρισματ-, πρῖσμα prism + -oid.

Pronunciation

prismatoid

/ˈprɪzmətɔɪd/