Webster's Revised Unabridged Dictionary · 1913

Refract

Refract (r?*fr$kt") , transitive verb

[Latin refractus, past participle of refringere; pref. re- re- + frangere to break: compare French réfracter. SEe FRacture, and compare Refrain, n.]

1.
To bend sharply and abruptly back; to break off.
2.
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.