What does "prismatical" mean?

Additional senses

1. 2.(Crystallog.) Same as Orthorhombic. Prismatic borax (Chem.), borax crystallized in the form of oblique prisms, with ten molecules of water; -- distinguished from octahedral borax. -- Prismatic colors (Opt.), the seven colors into which light is resolved when passed through a prism; primary colors. See Primary colors, under Color. -- Prismatic compass (Surv.), a compass having a prism for viewing a distant object and the compass card at the same time. -- Prismatic spectrum (Opt.), the spectrum produced by the passage of light through a prism.