D defs.my
Entry 2 senses Webster, 1913

Biprism

· Bi·prism · IPA
01 n. A prism whose refracting angle is very nearly 180 degrees.
  1. 1.
    A prism whose refracting angle is very nearly 180 degrees.
  2. 2.
    A combination of two short rectangular glass prisms cemented together at their diagonal faces so as to form a cube; -- called also optical cube. It is used in one form of photometer. Also: optical cube