Refract

Webster's Dictionary of the English Language

·noun To bend sharply and abruptly back; to break off.

II. Refract ·noun To break the natural course of, as rays of light orr heat, when passing from one transparent medium to another of different density; to cause to deviate from a direct course by an action distinct from reflection; as, a dense medium refrcts the rays of light as they pass into it from a rare medium.