What is "prismatical"

Prismatic \Pris*mat"ic\, Prismatical \Pris*mat"ic*al\, a. [Cf. F. prismatique.]

1. Resembling, or pertaining to, a prism; as, a prismatic form or cleavage.

2. Separated or distributed by a prism; formed by a prism; as, prismatic colors.

3. (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.

a. (alternative form of prismatic English)