refracting angle of a prism
Webster's Dictionary (GCIDE)
Refracting \Re*fract"ing\, a. Serving or tending to refract; as, a refracting medium. [1913 Webster]
Refracting angle of a prism (Opt.), the angle of a triangular prism included between the two sides through which the refracted beam passes in the decomposition of light.
Refracting telescope. (Opt.) See under Telescope. [1913 Webster]