Refractor, a word used largely in the field of optics, is a device or an instrument used for bending, redirecting or focusing light. Synonyms for refractor include lens, prism, telescope, glass, reflector, dioptometer, eyepiece and refractometer. These synonyms are used interchangeably to describe different types of optical instruments used for a variety of purposes. For instance, lens and prism are used to bend light in a particular direction, whereas a telescope is used to magnify images. Similarly, refractometer and dioptometer are used in the field of medicine and science to measure the refractive index of various materials and liquids.