n. turning or bending of any wave, such as light or sound wave, when it passes from one medium into another of different optical density
When you look at a stick inserted in water, it looks bent because of the refraction of the light by the water.
Sentence in Classic:
It outlined the facts with a cold precision unmodified by shade or colour, and refracted, as it were, from the blank walls of the surrounding limitations: she had opened windows from which no sky was ever visible.
House of Mirth By Edith Wharton Context